Floating Point Imprecision
It turns out that most fractional decimals cannot be represented precisely in binary and so there are a lot of fractional decimals that are approximated when stored in the computer causing what is known as floating point imprecision
How then do you decide that two floating points shall be considered equal?
That's called an epsilon (Greek Letter) which is used by
Is_equal_approx and the function name is self explanatory hence the vague documentation.
Is_equal_approx(1.333333333, 1.4) # yes it is
Same should apply for Rects, Basis, Vectors, Transforms