Returns the remainder of
(/ numerator denominator). If either
denominator is a float, the result will be a float.
The rounding behaviour for negative numbers is equivalent to Rust's
% operator -
if you need the Euclidean remainder, use
denominator is equal to
0, if the result would be an integer, it's an error.
(It's not an error to divide-by-zero when working with floating-point numbers, but the
remainder will be a