I can't figure how to use this bitflags

[glossy horizon]

The members are not public, i cannot access them.

I need to check if "Once" is true

pub const FlagsInt = u32;

pub fn FlagsMixin(comptime FlagType: type) type {
    comptime assert(@sizeOf(FlagType) == 4);
    return struct {
        pub fn toInt(self: FlagType) FlagsInt {
            return @as(FlagsInt, @bitCast(self));
        }
        pub fn fromInt(value: FlagsInt) FlagType {
            return @as(FlagType, @bitCast(value));
        }
        pub fn with(a: FlagType, b: FlagType) FlagType {
            return fromInt(toInt(a) | toInt(b));
        }
        pub fn only(a: FlagType, b: FlagType) FlagType {
            return fromInt(toInt(a) & toInt(b));
        }
        pub fn without(a: FlagType, b: FlagType) FlagType {
            return fromInt(toInt(a) & ~toInt(b));
        }
        pub fn hasAllSet(a: FlagType, b: FlagType) bool {
            return (toInt(a) & toInt(b)) == toInt(b);
        }
        pub fn hasAnySet(a: FlagType, b: FlagType) bool {
            return (toInt(a) & toInt(b)) != 0;
        }
        pub fn isEmpty(a: FlagType) bool {
            return toInt(a) == 0;
        }
        pub fn eql(a: FlagType, b: FlagType) bool {
            return toInt(a) == toInt(b);
        }
    };
}

why is it so unnecessarily complicated

the library author just expects me to know how to use this