pub fn group<S: Debug + PartialEq + Clone, const N: usize>(
items: &[S; N],
f: &impl Fn(S, S) -> S,
zero: S,
b: &impl Fn(S) -> S
) -> Result<(), &'static str>Expand description
Defines a group structure.
A group is a set of items along with an associative binary operation f
an identity element zero
and every element has an inverse element with respect to f