code: def validate_params(required, optional, params):
      
  
      missing_fields = [x for x in required if x not in params]
      if missing_fields:
          field_strings = ", ".join(missing_fields)
          raise Exception("Missing fields: %s" % field_strings)
  
      disallowed_fields = [x for x in params if x not in optional and x not in required]
      if disallowed_fields:
          field_strings = ", ".join(disallowed_fields)
          raise Exception("Disallowed fields: %s" % field_strings)
docs: Helps us validate the parameters for the request
  
      :param valid_options: a list of strings of valid options for the
                            api request
      :param params: a dict, the key-value store which we really only care about
                     the key which has tells us what the user is using for the
                     API request
  
      :returns: None or throws an exception if the validation fails