human
I wrote the below code

    class TheType(checked_class, ):
        __type__ = item_type
    TheType.__name__ = (item_type.__name__.capitalize() + suffix)
    if optional:
        def factory(argument):
            if (argument is None):
                return None
            else:
                return TheType(argument)
    else:
        factory = TheType
    return field(type=(optional_type(TheType) if optional else TheType), factory=factory, mandatory=True, initial=factory(initial))

What's a good function header?
assistant
#Here's a good function header.

def _sequence_field(checked_class, suffix, item_type, optional, initial):