Fix ValueError message and remove set() usage.

daspecster · daspecster · commit b77ed781fcfb · 2016-12-01T14:55:14.000-05:00
diff --git a/vision/google/cloud/vision/image.py b/vision/google/cloud/vision/image.py
@@ -41,12 +41,12 @@ class Image(object):
     """
 
     def __init__(self, client, content=None, filename=None, source_uri=None):
-        sources = set(source for source in (content, filename, source_uri)
-                      if source is not None)
+        sources = [source for source in (content, filename, source_uri)
+                   if source is not None]
         if len(sources) != 1:
             raise ValueError(
-                'Specify exactly one of \'content\', \'filename\', or'
-                '\'source_uri\'.')
+                'Specify exactly one of "content", "filename", or '
+                '"source_uri".')
 
         self.client = client
 
