code: public function tokenize($source, $name = null)
      {
          if (!$source instanceof Twig_Source) {
              @trigger_error(sprintf('Passing a string as the $source argument of %s() is deprecated since version 1.27. Pass a Twig_Source instance instead.', __METHOD__), E_USER_DEPRECATED);
              $source = new Twig_Source($source, $name);
          }
  
          if (null === $this->lexer) {
              $this->lexer = new Twig_Lexer($this);
          }
  
          return $this->lexer->tokenize($source);
      }
docs: Tokenizes a source code.
  
  @param string|Twig_Source $source The template source code
  @param string             $name   The template name (deprecated)
  
  @return Twig_TokenStream
  
  @throws Twig_Error_Syntax When the code is syntactically wrong