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section about funcs that dont return lists anymore
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‎tutorials/key_differences_between_python_2_and_3.html‎

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@@ -1762,6 +1762,7 @@ <h2 id="Sections">Sections<a class="anchor-link" href="#Sections">&#182;</a></h2
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<li><p><a href="#For-loop-variables-and-the-global-namespace-leak">For-loop variables and the global namespace leak</a></p></li>
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<li><p><a href="#Comparing-unorderable-types">Comparing unorderable types</a></p></li>
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<li><p><a href="#Parsing-user-inputs-via-input">Parsing user inputs via input()</a></p></li>
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<li><p><a href="#Returning-iterable-objects-instead-of-lists">Returning iterable objects instead of lists</a></p></li>
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<li><p><a href="#More-articles-about-Python-2-and-Python-3">More articles about Python 2 and Python 3</a></p></li>
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</ul>
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</div>
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</div>
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<div class="inner_cell">
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<div class="text_cell_render border-box-sizing rendered_html">
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<h2 id="Returning-iterable-objects-instead-of-lists">Returning iterable objects instead of lists<a class="anchor-link" href="#Returning-iterable-objects-instead-of-lists">&#182;</a></h2>
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</div>
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</div>
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</div>
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<div class="cell border-box-sizing text_cell rendered">
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<div class="prompt input_prompt">
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</div>
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<div class="inner_cell">
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<div class="text_cell_render border-box-sizing rendered_html">
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<p>[<a href="#Sections">back to the section-overview</a>]</p>
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</div>
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</div>
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</div>
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<div class="cell border-box-sizing text_cell rendered">
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<div class="prompt input_prompt">
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</div>
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<div class="inner_cell">
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<div class="text_cell_render border-box-sizing rendered_html">
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<p>As we have already seen in the <a href="#xrange"><code>xrange</code></a> section, some functions and methods return iterable objects in Python 3 now - instead of lists in Python 2.</p>
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<p>Since we usually iterate over those only once anyway, I think this change makes a lot of sense to save memory. However, it is also possible - in contrast to generators - to iterate over those multiple times if needed, it is aonly not so efficient.</p>
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<p>And for those cases where we really need the <code>list</code>-objects, we can simply convert the iterable object into a <code>list</code> via the <code>list()</code> function.</p>
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</div>
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</div>
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</div>
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<div class="cell border-box-sizing text_cell rendered">
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<div class="prompt input_prompt">
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</div>
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<div class="inner_cell">
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<div class="text_cell_render border-box-sizing rendered_html">
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<h4 id="python-2">Python 2</h4>
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</div>
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</div>
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</div>
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<div class="cell border-box-sizing code_cell rendered">
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<div class="input">
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<div class="prompt input_prompt">
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In&nbsp;[2]:
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</div>
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<div class="inner_cell">
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<div class="input_area">
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<div class="highlight"><pre><span class="k">print</span> <span class="s">&#39;Python&#39;</span><span class="p">,</span> <span class="n">python_version</span><span class="p">()</span>
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<span class="k">print</span> <span class="nb">range</span><span class="p">(</span><span class="mi">3</span><span class="p">)</span>
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<span class="k">print</span> <span class="nb">type</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">3</span><span class="p">))</span>
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</pre></div>
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</div>
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</div>
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</div>
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<div class="output_wrapper">
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<div class="output">
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<div class="output_area"><div class="prompt"></div>
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<div class="output_subarea output_stream output_stdout output_text">
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<pre>
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Python 2.7.6
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[0, 1, 2]
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&lt;type &apos;list&apos;&gt;
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</pre>
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</div>
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</div>
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</div>
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</div>
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</div>
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<div class="cell border-box-sizing text_cell rendered">
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<div class="prompt input_prompt">
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</div>
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<div class="inner_cell">
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<div class="text_cell_render border-box-sizing rendered_html">
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<h4 id="python-3">Python 3</h4>
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</div>
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</div>
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</div>
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<div class="cell border-box-sizing code_cell rendered">
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<div class="input">
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<div class="prompt input_prompt">
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In&nbsp;[7]:
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</div>
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<div class="inner_cell">
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<div class="input_area">
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<div class="highlight"><pre><span class="k">print</span><span class="p">(</span><span class="s">&#39;Python&#39;</span><span class="p">,</span> <span class="n">python_version</span><span class="p">())</span>
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<span class="k">print</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">3</span><span class="p">))</span>
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<span class="k">print</span><span class="p">(</span><span class="nb">type</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">3</span><span class="p">)))</span>
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<span class="k">print</span><span class="p">(</span><span class="nb">list</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">3</span><span class="p">)))</span>
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</pre></div>
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</div>
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</div>
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</div>
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<div class="output_wrapper">
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<div class="output">
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<div class="output_area"><div class="prompt"></div>
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<div class="output_subarea output_stream output_stdout output_text">
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<pre>
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Python 3.4.1
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range(0, 3)
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&lt;class &apos;range&apos;&gt;
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[0, 1, 2]
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</pre>
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</div>
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</div>
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</div>
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</div>
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</div>
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<div class="cell border-box-sizing text_cell rendered">
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<div class="prompt input_prompt">
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</div>
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<div class="inner_cell">
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<div class="text_cell_render border-box-sizing rendered_html">
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<p><br></p>
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</div>
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</div>
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</div>
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<div class="cell border-box-sizing text_cell rendered">
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<div class="prompt input_prompt">
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</div>
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<div class="inner_cell">
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<div class="text_cell_render border-box-sizing rendered_html">
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<p><strong>Some more commonly used functions and methods that don't return lists anymore in Python 3:</strong></p>
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<ul>
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<li><p><code>zip()</code></p></li>
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<li><p><code>map()</code></p></li>
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<li><p><code>filter()</code></p></li>
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<li><p>dictionary's <code>.keys()</code> method</p></li>
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<li><p>dictionary's <code>.values()</code> method</p></li>
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<li><p>dictionary's <code>.items()</code> method</p></li>
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</ul>
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</div>
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</div>
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</div>
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<div class="cell border-box-sizing text_cell rendered">
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<div class="prompt input_prompt">
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</div>
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<div class="inner_cell">
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<div class="text_cell_render border-box-sizing rendered_html">
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<p><br> <br></p>
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</div>
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</div>
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</div>
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<div class="cell border-box-sizing text_cell rendered">
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<div class="prompt input_prompt">
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</div>
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<div class="inner_cell">
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<div class="text_cell_render border-box-sizing rendered_html">
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<h2 id="More-articles-about-Python-2-and-Python-3">More articles about Python 2 and Python 3<a class="anchor-link" href="#More-articles-about-Python-2-and-Python-3">&#182;</a></h2>
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</div>
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</div>

‎tutorials/key_differences_between_python_2_and_3.ipynb‎

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"\n",
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"- [Parsing user inputs via input()](#Parsing-user-inputs-via-input)\n",
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"\n",
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"- [Returning iterable objects instead of lists](#Returning-iterable-objects-instead-of-lists)\n",
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"\n",
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"- [More articles about Python 2 and Python 3](#More-articles-about-Python-2-and-Python-3)"
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]
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},
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"<br>"
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]
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},
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{
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"cell_type": "heading",
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"level": 2,
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"metadata": {},
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"source": [
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"Returning iterable objects instead of lists"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"[[back to the section-overview](#Sections)]"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"As we have already seen in the [`xrange`](#xrange) section, some functions and methods return iterable objects in Python 3 now - instead of lists in Python 2. \n",
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"\n",
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"Since we usually iterate over those only once anyway, I think this change makes a lot of sense to save memory. However, it is also possible - in contrast to generators - to iterate over those multiple times if needed, it is aonly not so efficient.\n",
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"\n",
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"And for those cases where we really need the `list`-objects, we can simply convert the iterable object into a `list` via the `list()` function."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"#### Python 2"
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]
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},
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{
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"cell_type": "code",
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"collapsed": false,
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"input": [
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"print 'Python', python_version() \n",
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"\n",
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"print range(3) \n",
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"print type(range(3))"
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],
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"language": "python",
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"metadata": {},
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"outputs": [
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{
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"stream": "stdout",
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"Python 2.7.6\n",
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"[0, 1, 2]\n",
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"<type 'list'>\n"
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]
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}
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],
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"prompt_number": 2
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"#### Python 3"
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]
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},
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{
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"cell_type": "code",
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"collapsed": false,
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"input": [
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"print('Python', python_version())\n",
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"\n",
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"print(range(3))\n",
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"print(type(range(3)))\n",
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"print(list(range(3)))"
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],
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"language": "python",
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"metadata": {},
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"outputs": [
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{
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"output_type": "stream",
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"stream": "stdout",
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"text": [
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"Python 3.4.1\n",
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"range(0, 3)\n",
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"<class 'range'>\n",
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"[0, 1, 2]\n"
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]
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}
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],
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"prompt_number": 7
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<br>"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"**Some more commonly used functions and methods that don't return lists anymore in Python 3:**\n",
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"\n",
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"- `zip()`\n",
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"\n",
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"- `map()`\n",
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"\n",
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"- `filter()`\n",
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"\n",
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"- dictionary's `.keys()` method\n",
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"\n",
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"- dictionary's `.values()` method\n",
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"\n",
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"- dictionary's `.items()` method\n"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<br>\n",
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"<br>"
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]
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},
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{
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"cell_type": "heading",
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"level": 2,

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