docs: def _to_list(var):
      """
      Make variable to list.
  
      >>> _to_list(None)
      []
      >>> _to_list('whee')
      ['whee']
      >>> _to_list([None])
      [None]
      >>> _to_list((1, 2, 3))
      [1, 2, 3]
  
      :param var: variable of any type
      :return:    list
      """
      if isinstance(var, list):
          return var
      elif var is None:
          return []
      elif isinstance(var, str) or isinstance(var, dict):
          # We dont want to make a list out of those via the default constructor
          return [var]
      else:
          try:
              return list(var)
          except TypeError:
              return [var]