def __call__(self, field, **kwargs):
    for param, value in self.params.items():
        kwargs.setdefault(param, value)
return super(CustomInput, self).__call__(field, **kwargs)


class CustomTextInput(CustomInput):
    input_type = 'text'


class EditProfileForm(Form):
    pass
Python: WTForms Can I add a placeholder attribute when I init a field?