Assert an absolute difference is less than an expression.
Pseudocode: |Δ| < x
use assertables::*; let a = 10; let b = 13; let x = 4; assert_abs_diff_lt_x!(a, b, x);
assert_abs_diff_lt_x
assert_abs_diff_lt_x_as_result
debug_assert_abs_diff_lt_x