UD60x18 user-defined value type in Solidity

UD60x18.sol

// SPDX-License-Identifier: Unlicense
pragma solidity >=0.8.9;

/// @notice The unsigned 60.18-decimal fixed-point representation.
/// Can have up to 60 digits and up to 18 decimals.
type UD60x18 is uint256;
using { add, and, eq, gt, gte, leftShift, lt, lte, isZero, rightShift, uncheckedAdd } for UD60x18 global;

/// @notice Implements checked addition in the UD60x18 type.
function add(UD60x18 x, UD60x18 y) pure returns (UD60x18) {
    return UD60x18.wrap(UD60x18.unwrap(x) + UD60x18.unwrap(y));
}

/// @notice Implements the AND bitwise operation in the UD60x18 type.
function and(UD60x18 x, uint256 bits) pure returns (UD60x18) {
    return UD60x18.wrap(UD60x18.unwrap(x) & bits);
}

/// @notice Implements the equal (=) operation in the UD60x18 type.
function eq(UD60x18 x, UD60x18 y) pure returns (bool) {
    return UD60x18.unwrap(x) == UD60x18.unwrap(y);
}

function eq(UD60x18 x, uint256 y) pure returns (bool) {
    return UD60x18.unwrap(x) == UD60x18.unwrap(y);
}

/// @notice Implements the greater than (>) operation in the UD60x18 type.
function gt(UD60x18 x, UD60x18 y) pure returns (bool) {
    return UD60x18.unwrap(x) > UD60x18.unwrap(y);
}

/// @notice Implements the greater than or equal to (>=) operation in the UD60x18 type.
function gte(UD60x18 x, UD60x18 y) pure returns (bool) {
    return UD60x18.unwrap(x) >= UD60x18.unwrap(y);
}

/// @notice Implements a zero comparison check function in the UD60x18 type.
function isZero(UD60x18 x) pure returns (bool) {
    return UD60x18.unwrap(x) == 0;
}

/// @notice Implements the left shift operation in the UD60x18 type.
function leftShift(UD60x18 x, uint256 bits) pure returns (UD60x18) {
    return UD60x18.wrap(UD60x18.unwrap(x) << bits);
}

/// @notice Implements the lower than (<) operation in the UD60x18 type.
function lt(UD60x18 x, UD60x18 y) pure returns (bool) {
    return UD60x18.unwrap(x) < UD60x18.unwrap(y);
}

/// @notice Implements the lower than or equal to (<=) operation in the UD60x18 type.
function lte(UD60x18 x, UD60x18 y) pure returns (bool) {
    return UD60x18.unwrap(x) <= UD60x18.unwrap(y);
}

/// @notice Implements the right shift operation in the UD60x18 type.
function rightShift(UD60x18 x, uint256 bits) pure returns (UD60x18) {
    return UD60x18.wrap(UD60x18.unwrap(x) >> bits);
}

/// @notice Implements unchecked addition in the UD60x18 type.
function uncheckedAdd(UD60x18 x, UD60x18 y) pure returns (UD60x18) {
    unchecked {
        return UD60x18.wrap(UD60x18.unwrap(x) + UD60x18.unwrap(y));
    }
}