Certain languages like Python use leading indentation to denote blocks. Wouldn't it be nice if a Marpa frontend like the IRIF would have support for this? Well, the problem is that implementing the Off-side Rule is similarly difficult to implementing here-docs: both are non-context free constructs, but are easy to implement by maintaining state in the scanner.
Consider this piece of Python code:
def foo(x, y): return x + (2* y) foo(1, 2) #=> 5