code: def add_var_mb(table: PrettyTable,
                 vardict: Dict[str, str],
                 varname: str) -> None:
      
      valstr = vardict.get(varname, None)
      table.add_row([varname, val_mb(valstr), UNITS_MB])
docs: Adds a row to ``table`` for ``varname``, in megabytes.