mathlib3

1de192f4 - feat(algebra/ordered_ring): abs_cases lemma (#8124)

feat(algebra/ordered_ring): abs_cases lemma (#8124) This lemma makes the following type of argument work seamlessly: ```lean example (h : x<-1/2) : |x + 1| < |x| := by cases abs_cases (x + 1); cases abs_cases x; linarith ```