namper

import sys, functools

def private(member):
    @functools.wraps(member)
    def wrapper(*function_args):
      myself = member.__name__
      caller = sys._getframe(1).f_code.co_name
      if (not caller in dir(function_args[0]) and not caller is myself):
         raise Exception("%s called by %s is private"%(myself,caller))
      return member(*function_args)

namper

class SwitchIOField(Field):
    def __init__(
            self,
            input_field: Field,
            output_field: Field,
            *args, **kwargs
    ):
        # -- setting up input field
        self.input_field = input_field
        self.validators = input_field.validators