code: def is_pseq(arg):
      '''
      is_pseq(arg) yields True if arg is a persistent vector, a persistent list, a tuple, or a numpy
        array with its writeable flag off.
      '''
      if is_nparray(arg): return arg.flags['WRITEABLE'] == False
      return isinstance(arg, (tuple_type, pyr.PVector, pyr.PList)f is_pseq(arg):
      '''
      is_pseq(arg) yields True if arg is a persistent vector, a persistent list, a tuple, or a numpy
        array with its writeable flag off.
      '''
      if is_nparray(arg): return arg.flags['WRITEABLE'] == False
      return isinstance(arg, (tuple_type, pyr.PVector, pyr.PList))
docs: is_pseq(arg) yields True if arg is a persistent vector, a persistent list, a tuple, or a numpy
        array with its writeable flag off.