original_string: public function prefixKey($prefix)
      {
          if (empty($this->key)) {
              $this->key = $prefix;
          } else {
              $this->key = $prefix . '.' . $this->key;
          }
  
          return $this;
      }
code: public function prefixKey($prefix)
      {
          if (empty($this->key)) {
              $this->key = $prefix;
          } else {
              $this->key = $prefix . '.' . $this->key;
          }
  
          return $this;
      }
code_tokens: public function prefixKey ( $ prefix ) { if ( empty ( $ this -> key ) ) { $ this -> key = $ prefix ; } else { $ this -> key = $ prefix . '.' . $ this -> key ; } return $ this ; }
docstring: Prefixes the currently set key with a dot-notation parent.
  
  The (final) dot (.) should not be included in the prefix string.
  
  @param string $prefix
  @return $this
docstring_tokens: Prefixes the currently set key with a dot - notation parent .