code: def get_fields_with_prop(cls, prop_key):
          
  
          ret = []
  
          for key, val in getattr(cls, '_fields').items():
              if hasattr(val, prop_key):
                  ret.append((key, getattr(val, prop_key)))
          return ret
docs: Return a list of fields with a prop key defined
  
          Each list item will be a tuple of field name containing
          the prop key & the value of that prop key.
  
          :param prop_key: key name
          :return: list of tuples