def sum_of_digits(number):
    """
    What comes in:  An integer.
    What goes out:  Returns the sum of the digits in the given integer.
    Side effects:   None.
    Example:
      If the integer is 83135,
      this function returns (8 + 3 + 1 + 3 + 5), which is 20.
    """
    # ------------------------------------------------------------------
    # Students:
    #   Do NOT touch the above  sum_of_digits function - it has no TO DO.
    #   Do NOT copy code from this function.
    #
    # Instead, ** CALL ** this function as needed in the problems below.
    # ------------------------------------------------------------------
    if number < 0:
        number = -number

    digit_sum = 0
    while True:
        if number == 0:
            break
        digit_sum = digit_sum + (number % 10)
        number = number // 10

    return digit_sum