code: def prefixed_name(self) -> Tuple[YangIdentifier, Optional[YangIdentifier]]:
          
          i1 = self.yang_identifier()
          try:
              next = self.peek()
          except EndOfInput:
              return (i1, None)
          if next != ":":
              return (i1, None)
          self.offset += 1
          return (self.yang_identifier(), i1)
docs: Parse identifier with an optional colon-separated prefix.