Iterator of decimals beginning with this Dec and ending with the
other Dec, stepping by 1.0. (Use Dec.until instead to end with
the other Dec minus one.) Returns an empty iterator if this Dec
is greater than the other.
expect Iter.fold(Dec.to(1.0, 4.0), [], |acc, item| acc.append(item)) == [1.0, 2.0, 3.0, 4.0]
expect Iter.fold(Dec.to(-2.0, 1.0), [], |acc, item| acc.append(item)) == [-2.0, -1.0, 0.0, 1.0]
expect Iter.fold(Dec.to(5.0, 2.0), [], |acc, item| acc.append(item)) == []