code: def _val_from_env(self, env, attr):
          
          val = os.environ[env]
          if attr in ('rules', 'exclude_rules'):
              return self._rules_from_env(val)
          elif attr == 'priority':
              return dict(self._priority_from_env(val))
          elif attr in ('wait_command', 'history_limit', 'wait_slow_command',
                        'num_close_matches'):
              return int(val)
          elif attr in ('require_confirmation', 'no_colors', 'debug',
                        'alter_history', 'instant_mode'):
              return val.lower() == 'true'
          elif attr == 'slow_commands':
              return val.split(':')
          else:
              return val
docs: Transforms env-strings to python.