private function hash_to_key($hash)
     {
        if (array_key_exists($hash, $this->map_hash_to_key)) {
            return $this->map_hash_to_key[$hash];
        } else {
            throw new \OutOfBoundsException(sprintf(
                'Hash "%s" has not been created',
                $hash
            ));
        }
     }
private function hash_to_key($hash)
     {
        if (array_key_exists($hash, $this->map_hash_to_key)) {
            return $this->map_hash_to_key[$hash];
        } else {
            throw new \OutOfBoundsException(sprintf(
                'Hash "%s" has not been created',
                $hash
            ));
        }
     }
private function hash_to_key ( $ hash ) { if ( array_key_exists ( $ hash , $ this -> map_hash_to_key ) ) { return $ this -> map_hash_to_key [ $ hash ] ; } else { throw new \ OutOfBoundsException ( sprintf ( 'Hash "%s" has not been created' , $ hash ) ) ; } }
Lookup the key for the given hash.

@param string $hash
@return mixed
Lookup the key for the given hash .