Extend type hints from outside

[mflova]

When type hinting new pandas accessors, these will not be properly type hinted. Consider the possibility of adding hardcoded lines and imports. Lines to be added to the class. Something like:

{extra_imports}

class MyDataFrame(pd.DataFrame):

    {line_given_by_the_user}

    @overload  # type: ignore
    def __getitem__(self, key: Literal['HA40+']) -> pd.Series["Quantity"]:
        ...

Where line_given_by_the_user can be: pint: PintAccessor and {extra_imports} being PintAccessor corresponding import

How this information is given is still to be decided

EDIT: Another alternative would be to scan all accessors within a pandas dataframe and include them in the class scope of the dataframe (including associated import)