function isHandleValid(bytes32 _handle) public pure returns (bool) {
        if (_handle == 0x0) {
            return false;
        }
        bool padded;
        for (uint i = 0; i < 32; i++) {
            byte char = byte(bytes32(uint(_handle) * 2 ** (8 * i)));
            
            if (char == 0x0) {
                padded = true;
                continue;
            }
            
            if (char >= 0x30  && char <= 0x39 && !padded) {
                continue;
            }
            
            if (char >= 0x61  && char <= 0x7A && !padded) {
                continue;
            }
            
            if (char == 0x5F && !padded) {
                continue;
            }
            return false;
        }
        return true;
    }