Camel to Snake case

camel_to_snake_case.py

def camel_to_snake_case(name: str) -> str:
    #  ord('a') == 97
    r = []
    new_group = [name[0].lower()]
    for c in name[1:]:
        if 97 <= ord(c) <= 122:
            new_group.append(c)
        else:
            r.append("".join(new_group))
            new_group = [c.lower()]

    r.append("".join(new_group))
    return "_".join(r)

#  test cases
def test_camel_to_snake_case():
    assert "a" == camel_to_snake_case("A")
    assert "a_b_c" == camel_to_snake_case("ABC")
    assert "ab_c" == camel_to_snake_case("AbC")
    assert "a_bc" == camel_to_snake_case("ABc")
    assert "ab_cd" == camel_to_snake_case("AbCd")