code: def get_field(self, field_type):
          
          for field in self.oxm_match_fields:
              if field.oxm_field == field_type:
                  return field.oxm_value
  
          return None
docs: Return the value for the 'field_type' field in oxm_match_fields.
  
          Args:
              field_type (~pyof.v0x04.common.flow_match.OxmOfbMatchField,
                          ~pyof.v0x04.common.flow_match.OxmMatchFields):
                  The type of the OXM field you want the value.
  
          Returns:
              The integer number of the 'field_type' if it exists. Otherwise
              return None.