original_string: public function lastIndexOf($string, $offset = null) {
  		if (null === $offset) {
  			$offset = $this->length();
  		} else {
  			$offset = $this->prepareOffset($offset);
  		}
  
  		if ($string === '') {
  			return $offset;
  		}
  
  		/* Converts $offset to a negative offset as strrpos has a different
  		 * behavior for positive offsets. */
  		return mb_strrpos($this, (string) $string, $offset - $this->length(), $this->encoding);
  	}
code: public function lastIndexOf($string, $offset = null) {
  		if (null === $offset) {
  			$offset = $this->length();
  		} else {
  			$offset = $this->prepareOffset($offset);
  		}
  
  		if ($string === '') {
  			return $offset;
  		}
  
  		/* Converts $offset to a negative offset as strrpos has a different
  		 * behavior for positive offsets. */
  		return mb_strrpos($this, (string) $string, $offset - $this->length(), $this->encoding);
  	}
code_tokens: public function lastIndexOf ( $ string , $ offset = null ) { if ( null === $ offset ) { $ offset = $ this -> length ( ) ; } else { $ offset = $ this -> prepareOffset ( $ offset ) ; } if ( $ string === '' ) { return $ offset ; } /* Converts $offset to a negative offset as strrpos has a different
  		 * behavior for positive offsets. */ return mb_strrpos ( $ this , ( string ) $ string , $ offset - $ this -> length ( ) , $ this -> encoding ) ; }
docstring: Returns the last index of a given string, starting at the optional offset
  
  @param string $string
  @param int $offset
  @return int|boolean int for the index or false if the given string doesn't occur
docstring_tokens: Returns the last index of a given string starting at the optional offset