collection.find_one should return None if nothing is found

[alfredodeza]

Because otherwise it will raise IndexError while attempting to get the first item on the list.

Which forces a consumer to dance around it by:

documents = collection.find(doc, limit=1)
if documents:
    document = documents[0]

Or the same with a try/except that catches IndexError.

[plutec]

This issue doesn't exist in the current code. You fixed with issue #3 .