code: def merge(self, groups=None, group_name=None, group_type=None):
      """
      Convert this TableSet into a single table. This is the inverse of
      :meth:`.Table.group_by`.
  
      Any `row_names` set on the merged tables will be lost in this
      process.
  
      :param groups:
          A list of grouping factors to add to merged rows in a new column.
          If specified, it should have exactly one element per :class:`Table`
          in the :class:`TableSet`. If not specified or None, the grouping
          factor will be the name of the :class:`Row`'s original Table.
      :param group_name:
          This will be the column name of the grouping factors. If None,
          defaults to the :attr:`TableSet.key_name`.
      :param group_type:
          This will be the column type of the grouping factors. If None,
          defaults to the :attr:`TableSet.key_type`.
      :returns:
          A new :class:`Table`.
      """
      if type(groups) is not list and groups is not None:
          raise ValueError("Groups must be None or a list.")
  
      if type(groups) is list and len(groups) != len(self):
          raise ValueError(
              "Groups length must be equal to TableSet length."
          )
  
      column_names = list(self._column_names)
      column_types = list(self._column_types)
  
      column_names.insert(
          0, group_name if group_name else self._key_name
      )
      column_types.insert(
          0, group_type if group_type else self._key_type
      )
  
      rows = []
  
      for index, (key, table) in enumerate(self.items()):
          for row in table._rows:
              if groups is None:
                  rows.append(Row((key,) + tuple(row), column_names))
              else:
                  rows.append(
                      Row((groups[index],) + tuple(row), column_names)
                  )
  
      return Table(rows, column_names, column_types)
  
label_desc: Use image node_id 1 for calling a global function with example usage: merge(groups, group_name, group_type) and returns: Table