abstract contract ModuleBase is IModule {

    /* ============ State Variables ============ */

    // Address of the controller
    IController public controller;

    /* ============ Modifiers ============ */

    modifier onlySetManager(ISetToken _setToken, address _caller) {
        require(isSetManager(_setToken, _caller), "Must be the SetToken manager");
        _;
    }

    modifier onlyValidAndInitializedSet(ISetToken _setToken) {
        require(isSetValidAndInitialized(_setToken), "Must be a valid and initialized SetToken");
        _;
    }

    /**
     * Throws if the sender is not a SetToken's module or module not enabled
     */
    modifier onlyModule(ISetToken _setToken) {
        require(
            _setToken.moduleStates(msg.sender) == ISetToken.ModuleState.INITIALIZED,
            "Only the module can call"
        );

        require(
            controller.isModule(msg.sender),
            "Module must be enabled on controller"
        );
        _;
    }

    /**
     * Utilized during module initializations to check that the module is in pending state
     * and that the SetToken is valid
     */
    modifier onlyValidAndPendingSet(ISetToken _setToken) {
        require(controller.isSet(address(_setToken)), "Must be controller-enabled SetToken");
        require(isSetPendingInitialization(_setToken), "Must be pending initialization");        
        _;
    }

    /* ============ Constructor ============ */

    /**
     * Set state variables and map asset pairs to their oracles
     *
     * @param _controller             Address of controller contract
     */
    constructor(IController _controller) public {
        controller = _controller;
    }

    /* ============ Internal Functions ============ */

    /**
     * Transfers tokens from an address (that has set allowance on the module).
     *
     * @param  _token          The address of the ERC20 token
     * @param  _from           The address to transfer from
     * @param  _to             The address to transfer to
     * @param  _quantity       The number of tokens to transfer
     */
    function transferFrom(IERC20 _token, address _from, address _to, uint256 _quantity) internal {
        ExplicitERC20.transferFrom(_token, _from, _to, _quantity);
    }

    /**
     * Returns true if the module is in process of initialization on the SetToken
     */
    function isSetPendingInitialization(ISetToken _setToken) internal view returns(bool) {
        return _setToken.isPendingModule(address(this));
    }

    /**
     * Returns true if the address is the SetToken's manager
     */
    function isSetManager(ISetToken _setToken, address _toCheck) internal view returns(bool) {
        return _setToken.manager() == _toCheck;
    }

    /**
     * Returns true if SetToken must be enabled on the controller 
     * and module is registered on the SetToken
     */
    function isSetValidAndInitialized(ISetToken _setToken) internal view returns(bool) {
        return controller.isSet(address(_setToken)) &&
            _setToken.isInitializedModule(address(this));
    }
}
/**
 * @title ModuleBase
 * @author Set Protocol
 *
 * Abstract class that houses common Module-related state and functions.
 */
function isSetPendingInitialization(ISetToken _setToken) internal view returns(bool) {
        return _setToken.isPendingModule(address(this));
    }
/**
 * Returns true if the module is in process of initialization on the SetToken
 */