library Roles {
    struct Role {
        mapping (address => bool) bearer;
    }

    /**
     * @dev give an address access to this role
     */
    function add(Role storage role, address addr)
    internal
    {
        role.bearer[addr] = true;
    }

    /**
     * @dev remove an address' access to this role
     */
    function remove(Role storage role, address addr)
    internal
    {
        role.bearer[addr] = false;
    }

    /**
     * @dev check if an address has this role
     * // reverts
     */
    function check(Role storage role, address addr)
    view
    internal
    {
        require(has(role, addr));
    }

    /**
     * @dev check if an address has this role
     * @return bool
     */
    function has(Role storage role, address addr)
    view
    internal
    returns (bool)
    {
        return role.bearer[addr];
    }
}
/**
 * @title Roles
 * @author Francisco Giordano (@frangio)
 * @dev Library for managing addresses assigned to a Role.
 *      See RBAC.sol for example usage.
 */
function remove(Role storage role, address addr)
internal
{
    role.bearer[addr] = false;
}

/**
 * @dev remove an address' access to this role
 */