code: def parse_iterable(self, stream, start, end):
          
          values = []
  
          self.expect(stream, start)
          self.skip_whitespace_or_comment(stream)
  
          if self.has_next(end, stream):
              self.expect(stream, end)
              return values
  
          while 1:
              self.skip_whitespace_or_comment(stream)
              values.append(self.parse_value(stream))
              self.skip_whitespace_or_comment(stream)
  
              if self.has_next(end, stream):
                  self.expect(stream, end)
                  return values
  
              self.expect(stream, self.seporator)
docs: Sequence ::= SequenceStart WSC SequenceValue? WSC SequenceEnd
          Set := SetStart WSC SequenceValue? WSC SetEnd
          SequenceValue ::= Value (WSC SeparatorSymbol WSC Value)*