IProvider.sol

// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.7.6;
pragma abicoder v2;

interface IProvider {

    function smartYield() external view returns (address);

    function controller() external view returns (address);

    function underlyingFees() external view returns (uint256);

    // deposit underlyingAmount_ into provider, add takeFees_ to fees
    function _depositProvider(uint256 underlyingAmount_, uint256 takeFees_) external;

    // withdraw underlyingAmount_ from provider, add takeFees_ to fees
    function _withdrawProvider(uint256 underlyingAmount_, uint256 takeFees_) external;

    function _takeUnderlying(address from_, uint256 amount_) external;

    function _sendUnderlying(address to_, uint256 amount_) external returns (bool);

    function transferFees() external;

    // current total underlying balance as measured by the provider pool
    function underlyingBalance() external returns (uint256);

}