original_string: public function subject($subject = null)
      {
          if ($subject !== null) {
              $this->_subject = $subject;
  
              return $this;
          }
  
          return $this->_subject;
      }
code: public function subject($subject = null)
      {
          if ($subject !== null) {
              $this->_subject = $subject;
  
              return $this;
          }
  
          return $this->_subject;
      }
code_tokens: public function subject ( $ subject = null ) { if ( $ subject !== null ) { $ this -> _subject = $ subject ; return $ this ; } return $ this -> _subject ; }
docstring: Gets or sets message's subject.
  
  @param string $subject Subject
  @return $this|string When new value is set, $this is returned for allowing
  method chaining. When getting value a string will be returned
docstring_tokens: Gets or sets message s subject .