import string


def is_number(message, i):
    """
    Check to see if the values given make a number.

    True: .1
    True: -1
    True: 1
    True: -.1
    False: ..
    False: --
    False: a
    False: -a
    False: .a
    """
    check_one = bool(message[i] == '.' or message[i] == '-')
    check_two = bool(check_one and message[i + 1] in string.digits)
    check_three = bool(message[i] and message[i] in string.digits)
    check_four = bool(message[i] == '-' and message[i + 1] == '.')
    check_five = bool(check_four and message[i + 2] in string.digits)
    return check_two or check_three or check_five