Example:

dct = {"": ""}

# ok
trans = str.maketrans(dct)
"".translate(trans)

# err
"".translate(str.maketrans(dct))

• What is the actual behavior/output?

maketrans.py:8: error: Argument 1 to "maketrans" of "str" has incompatible type "Dict[str, str]"; expected "Union[Dict[int, Union[int, str, None]], Dict[str, Union[int, str, None]], Dict[Union[str, int], Union[int, str, None]]]"

• What is the behavior/output you expect?

No error.

• What are the versions of mypy and Python you are using?

I tested both mypy 0.610 and mypy 0.620+dev-0ca6bf9ce63439a1e8bcc4dec80ef12f8414cb87 with Python 3.6.5; behavior is identical.