docs: def _get_select_commands(self, source, tables):
          """
          Create select queries for all of the tables from a source database.
  
          :param source: Source database name
          :param tables: Iterable of table names
          :return: Dictionary of table keys, command values
          """
          # Create dictionary of select queries
          row_queries = {tbl: self.select_all(tbl, execute=False) for tbl in
                         tqdm(tables, total=len(tables), desc='Getting {0} select queries'.format(source))}
  
          # Convert command strings into lists of commands
          for tbl, command in row_queries.items():
              if isinstance(command, str):
                  row_queries[tbl] = [command]
  
          # Pack commands into list of tuples
          return [(tbl, cmd) for tbl, cmds in row_queries.items() for cmd in cmds]