interface o_Inter{
    function invest(uint256 _amount, uint256 _mode) external returns (uint256); // check return type and value
    function redeem(uint256 _shares) external returns (uint256); // check return type and value
    function balanceOf(address account) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
	function AaveAPR() external view returns (uint256);
	function FulcrumAPR() external view returns (uint256);
	function CompoundAPR() external view returns (uint256);
}
function balanceOf(address account) external view returns (uint256);

// check return type and value