def sjoiner(inbox, s=None, join="<STR_LIT>"):
return join.join([input_ for i, input_ in enumerate(inbox) if i in s])<EOL>
String joins input with indices in s.

Arguments:

  - s(sequence) [default: ``None``] ``tuple`` or ``list`` of indices of the
    elements which will be joined.
  - join(``str``) [default: ``""``] String which will join the elements of 
    the inbox i.e. ``join.join()``.