original_string: public function add($key, $value, $flag = null, $expire = 0) {
      // Sending of a key of 'null' or an unset value is a failure.
      if (is_null($key)) {
        return false;
      }
  
      try {
       $set_results = MemcacheUtils::setMultiWithPolicy(array($key => $value),
                                                        $expire,
                                                        SetPolicy::ADD);
      } catch (Error $e) {
        return false;
      }
      return $set_results[0] == SetStatusCode::STORED;
    }
code: public function add($key, $value, $flag = null, $expire = 0) {
      // Sending of a key of 'null' or an unset value is a failure.
      if (is_null($key)) {
        return false;
      }
  
      try {
       $set_results = MemcacheUtils::setMultiWithPolicy(array($key => $value),
                                                        $expire,
                                                        SetPolicy::ADD);
      } catch (Error $e) {
        return false;
      }
      return $set_results[0] == SetStatusCode::STORED;
    }
code_tokens: public function add ( $ key , $ value , $ flag = null , $ expire = 0 ) { // Sending of a key of 'null' or an unset value is a failure. if ( is_null ( $ key ) ) { return false ; } try { $ set_results = MemcacheUtils :: setMultiWithPolicy ( array ( $ key => $ value ) , $ expire , SetPolicy :: ADD ) ; } catch ( Error $ e ) { return false ; } return $ set_results [ 0 ] == SetStatusCode :: STORED ; }
docstring: Adds a new item to the cache. Will fail if the key is already present in
  the cache.
  
  @param string $key The key associated with the value added to the cache.
  
  @param mixed $value The value to add to the cache.
  
  @param int $flag This parameter is present only for compatibility and is
  ignored.
  
  @param int $expire The delay before the item is removed from the cache. If
  $expire <= 2592000 then it is interpreted as the number
  of seconds from the time of the call to wait before
  removing the item from the cache. If $expire > 2592000
  then it is interpreted as the absolute Unix epoch time
  when the value will expire.
  
  @return bool true if the item was successfully added to the cache, false
  otherwise.
docstring_tokens: Adds a new item to the cache . Will fail if the key is already present in the cache .