LibRoles.sol

// SPDX-License-Identifier: MIT
pragma solidity =0.7.5;


/**
 * @dev Library for managing addresses assigned to a Role.
 */
library Roles {
    struct Role
    {
        mapping (address => bool) bearer;
    }

    /**
     * @dev Give an account access to this role.
     */
    function add(
        Role storage role,
        address account
    )
        internal
    {
        require(!has(role, account), "Roles: account already has role");
        role.bearer[account] = true;
    }

    /**
     * @dev Remove an account's access to this role.
     */
    function remove(
        Role storage role,
        address account
    )
        internal
    {
        require(has(role, account), "Roles: account does not have role");
        role.bearer[account] = false;
    }

    /**
     * @dev Check if an account has this role.
     *
     * @return bool
     */
    function has(
        Role storage role,
        address account
    )
        internal
        view
        returns (bool)
    {
        require(account != address(0), "Roles: account is the zero address");
        return role.bearer[account];
    }
}