def METHOD_NAME() -> bool:
    nonlocal number_found_dot
    char = stream[index]
    is_dot = char == "."
    is_num = str.isdigit(char) or (start == index and char == "-") or (is_dot and not number_found_dot)
    if not number_found_dot and is_dot:
        number_found_dot = True
    return not is_num