message: refactoring: 'if' syntax deduplication
diff: @@ -363,9 +363,7 @@ def _get_grouped_variables(vars_to_warm_start):
  # out the list.
  grouped_variables = {}
  for v in list_of_vars:
  - if not isinstance(v, list):
  - var_name = _infer_var_name([v])
  - else:
  + v = [v] if not isinstance(v, list) else v
  var_name = _infer_var_name(v)
  grouped_variables.setdefault(var_name, []).append(v)
  