function depositToken(address _token, uint _amount) public whenNotPaused {
        
        require(_token != address(0));

        require(ERC20(_token).transferFrom(msg.sender, this, _amount));
        tokens[_token][msg.sender] = SafeMath.add(tokens[_token][msg.sender], _amount);

        emit Deposit(_token, msg.sender, _amount, tokens[_token][msg.sender]);
    }