code: def from_string(type_string):
      '''Returns the correct constant for a given string.
  
      @raises InvalidCompositeTypeError
  
      '''
      if type_string == NONE:
          return NONE
      elif type_string == PERIODIC_EC_SHARED:
          return PERIODC_EC_SHARED
      elif type_string == PERIODIC_STATE_SHARED:
          return PERIODIC_STATE_SHARED
      elif type_string == GROUPING:
          return GROUPING
      elif type_string == FSM_EC_SHARED:
          return FSM_EC_SHARED
      elif type_string == FSM_STATE_SHARED:
          return FSM_STATE_SHARED
      else:
          raise InvalidCompositeTypeError(type_stringf from_string(type_string):
      '''Returns the correct constant for a given string.
  
      @raises InvalidCompositeTypeError
  
      '''
      if type_string == NONE:
          return NONE
      elif type_string == PERIODIC_EC_SHARED:
          return PERIODC_EC_SHARED
      elif type_string == PERIODIC_STATE_SHARED:
          return PERIODIC_STATE_SHARED
      elif type_string == GROUPING:
          return GROUPING
      elif type_string == FSM_EC_SHARED:
          return FSM_EC_SHARED
      elif type_string == FSM_STATE_SHARED:
          return FSM_STATE_SHARED
      else:
          raise InvalidCompositeTypeError(type_string)
docs: Returns the correct constant for a given string.
  
      @raises InvalidCompositeTypeError