code: def calcsize(fmt):
    
  
    formatdef, endianness, i = getmode(fmt)
    num = 0
    result = 0
    while i < len(fmt):
      num, i = getNum(fmt, i)
      cur = fmt[i]
      try:
        format = formatdef[cur]
      except KeyError:
        raise StructError("%s is not a valid format" % cur)
      if num != None:
        result += num * format['size']
      else:
        result += format['size']
      num = 0
      i += 1
    return result
docs: calcsize(fmt) -> int
    Return size of C struct described by format string fmt.
    See struct.__doc__ for more on format strings.