Range Expressions

Someone, I forget who, gave feedback suggesting making "by" a binary operator so

1 to 10 by 2 means ((1 to 10) by 2) i.e. 1, 3, 5, 7, 9 
1 to 10 by -1 gives 10, 9, 8, 7, 6, 5, 4, 3, 2, 1
("A", "B", "C", "D") by 2 gives ("A", "C")
("A", "B", "C", "D") by -2 gives ("D", "B")

I've adopted this suggestion in my latest draft.

Michael Kay
Saxonica