Levenshtein metric on canonical anchors: d(kitten,sitting) = 3, d(x,x)=0, symmetric

Sympy/stdlib-exact witness of the Levenshtein metric on the canonical 'kitten' → 'sitting' anchor (Levenshtein 1966 original paper example). Edit sequence: kitten → sitten (sub k→s) → sittin (sub e→i) → sitting (ins g). Minimum edit…