docs: def joined_seq(seq, sep=None):
      r"""Join a sequence into a tuple or a concatenated string
  
      >>> joined_seq(range(3), ', ')
      '0, 1, 2'
      >>> joined_seq([1, 2, 3])
      (1, 2, 3)
      """
      joined_seq = tuple(seq)
      if isinstance(sep, basestring):
          joined_seq = sep.join(str(item) for item in joined_seq)
      return joined_seq