original_string: public function setSystemMessageType($messageType): Envelope
      {
          if (!in_array($messageType, static::getLetterTypeOptions())) {
              throw new InvalidArgumentException(
                  sprintf('Property %s is not supported for %s', $messageType, __FUNCTION__)
              );
          }
  
          $this->data['letterType']['systemMessageType'] = $messageType;
  
          return $this;
      }
code: public function setSystemMessageType($messageType): Envelope
      {
          if (!in_array($messageType, static::getLetterTypeOptions())) {
              throw new InvalidArgumentException(
                  sprintf('Property %s is not supported for %s', $messageType, __FUNCTION__)
              );
          }
  
          $this->data['letterType']['systemMessageType'] = $messageType;
  
          return $this;
      }
code_tokens: public function setSystemMessageType ( $ messageType ) : Envelope { if ( ! in_array ( $ messageType , static :: getLetterTypeOptions ( ) ) ) { throw new InvalidArgumentException ( sprintf ( 'Property %s is not supported for %s' , $ messageType , __FUNCTION__ ) ) ; } $ this -> data [ 'letterType' ] [ 'systemMessageType' ] = $ messageType ; return $ this ; }
docstring: Specify the type of E-POST letter
  
  @param string $messageType
  
  @return self
  @throws InvalidArgumentException
docstring_tokens: Specify the type of E - POST letter