code: def _is_on_symbol(self, offset):
          "Is this offset on a symbol?"
          if not ROPE_AVAILABLE:
              return False
          data = self.resource.read()
          if offset >= len(data):
              return False
          if data[offset] != '_' and not data[offset].isalnum():
              return False
          word = worder.get_name_at(self.resource, offset)
          if word:
              return True
          else:
              return Falsf _is_on_symbol(self, offset):
          "Is this offset on a symbol?"
          if not ROPE_AVAILABLE:
              return False
          data = self.resource.read()
          if offset >= len(data):
              return False
          if data[offset] != '_' and not data[offset].isalnum():
              return False
          word = worder.get_name_at(self.resource, offset)
          if word:
              return True
          else:
              return False
docs: Is this offset on a symbol?