interface IGovernable {

    /***************************************
    EVENTS
    ***************************************/

    /// @notice Emitted when pending Governance is set.
    event GovernancePending(address pendingGovernance);
    /// @notice Emitted when Governance is set.
    event GovernanceTransferred(address oldGovernance, address newGovernance);
    /// @notice Emitted when Governance is locked.
    event GovernanceLocked();

    /***************************************
    VIEW FUNCTIONS
    ***************************************/

    /// @notice Address of the current governor.
    function governance() external view returns (address);

    /// @notice Address of the governor to take over.
    function pendingGovernance() external view returns (address);

    /// @notice Returns true if governance is locked.
    function governanceIsLocked() external view returns (bool);

    /***************************************
    MUTATORS
    ***************************************/

    /**
     * @notice Initiates transfer of the governance role to a new governor.
     * Transfer is not complete until the new governor accepts the role.
     * Can only be called by the current [**governor**](/docs/protocol/governance).
     * @param pendingGovernance_ The new governor.
     */
    function setPendingGovernance(address pendingGovernance_) external;

    /**
     * @notice Accepts the governance role.
     * Can only be called by the new governor.
     */
    function acceptGovernance() external;

    /**
     * @notice Permanently locks this contract's governance role and any of its functions that require the role.
     * This action cannot be reversed.
     * Before you call it, ask yourself:
     *   - Is the contract self-sustaining?
     *   - Is there a chance you will need governance privileges in the future?
     * Can only be called by the current [**governor**](/docs/protocol/governance).
     */
    function lockGovernance() external;
}
/**
 * @title IGovernable
 * @author solace.fi
 * @notice Enforces access control for important functions to [**governor**](/docs/protocol/governance).
 *
 * Many contracts contain functionality that should only be accessible to a privileged user. The most common access control pattern is [OpenZeppelin's `Ownable`](https://docs.openzeppelin.com/contracts/4.x/access-control#ownership-and-ownable). We instead use `Governable` with a few key differences:
 * - Transferring the governance role is a two step process. The current governance must [`setPendingGovernance(pendingGovernance_)`](#setpendinggovernance) then the new governance must [`acceptGovernance()`](#acceptgovernance). This is to safeguard against accidentally setting ownership to the wrong address and locking yourself out of your contract.
 * - `governance` is a constructor argument instead of `msg.sender`. This is especially useful when deploying contracts via a [`SingletonFactory`](./ISingletonFactory).
 * - We use `lockGovernance()` instead of `renounceOwnership()`. `renounceOwnership()` is a prerequisite for the reinitialization bug because it sets `owner = address(0x0)`. We also use the `governanceIsLocked()` flag.
 */
function pendingGovernance() external view returns (address);

/// @notice Address of the governor to take over.