docs: def encode(arg, delimiter=None, encodeseq=None, encoded=tuple()):
      '''Encode a single argument for the file-system'''
      arg = coerce_unicode(arg, _c.FSQ_CHARSET)
      new_arg = sep = u''
      delimiter, encodeseq = delimiter_encodeseq(
          _c.FSQ_DELIMITER if delimiter is None else delimiter,
          _c.FSQ_ENCODE if encodeseq is None else encodeseq,
          _c.FSQ_CHARSET)
  
      # validate encoded tuple
      for enc in encoded:
          enc = coerce_unicode(enc, _c.FSQ_CHARSET)
          try:
              enc = enc.encode('ascii')
          except UnicodeEncodeError:
              raise FSQEncodeError(errno.EINVAL, u'invalid encoded value: {0}'\
                                   u' non-ascii'.format(enc))
      # char-wise encode walk
      for seq in arg:
          if seq == delimiter or seq == encodeseq or seq in _ENCODED + encoded:
              h_val = hex(ord(seq))
              # front-pad with zeroes
              if 3 == len(h_val):
                  h_val = sep.join([h_val[:2], u'0', h_val[2:]])
              if 4 != len(h_val):
                  raise FSQEncodeError(errno.EINVAL, u'invalid hex ({0}) for'\
                                       ' encode-target: {1}'.format(h_val, seq))
              seq = sep.join([encodeseq, h_val[2:]])
  
          new_arg = sep.join([new_arg, seq])
  
      return new_arg