# tree.py (final)

from typing import Tuple, Iterable, Dict, List, DefaultDict, TypeVar

from collections import defaultdict

T = TypeVar('T')

Relation = Tuple[T, T]

def create_tree(tuples: Iterable[Relation]) -> DefaultDict[T, List[T]]:

"""

Return a tree given tuples of (child, father)

The tree structure is as follows:

tree = {node_1: [node_2, node_3],

node_2: [node_4, node_5, node_6],

node_6: [node_7, node_8]}

"""

# convert to dict

tree: DefaultDict[T, List[T]] = defaultdict(list)

for pair in tuples:

child, father = pair

if father:

tree[father].append(child)

return tree

print(create_tree([(2.0, 1.0), (3.0, 1.0), (4.0, 3.0), (1.0, 6.0)]))

"""

Generic Classes

"""

def return_values() -> Iterable[float]:

yield 4.0

yield 5.0

yield 6.0

def chain(*args: Iterable[T]) -> Iterable[T]:

for arg in args:

yield from arg

print(list(chain([1, 2, 3], return_values(), 'string')))