code: def header(self, name, data, data_type, **kwargs):
          
          if self.client_side_validation:
              data = self.validate(data, name, required=True, **kwargs)
          try:
              if data_type in ['[str]']:
                  data = ["" if d is None else d for d in data]
  
              output = self.serialize_data(data, data_type, **kwargs)
              if data_type == 'bool':
                  output = json.dumps(output)
          except SerializationError:
              raise TypeError("{} must be type {}.".format(name, data_type))
          else:
              return str(output)
docs: Serialize data intended for a request header.
  
          :param data: The data to be serialized.
          :param str data_type: The type to be serialized from.
          :rtype: str
          :raises: TypeError if serialization fails.
          :raises: ValueError if data is None