code: def test_format_unhashed_feature():
      assert format_feature([]) == ""
      assert format_feature([{"name": "foo", "sign": 1}]) == "foo"
      assert format_feature(
          [{"name": " foo", "sign": -1}]
      ) == "(-){}foo".format(_SPACE)
      assert (
          format_feature(
              [{"name": "foo", "sign": 1}, {"name": "bar", "sign": -1}]
          )
          == "foo | (-)bar"
      )
  
imports: from eli5.formatters import FormattedFeatureName
  from eli5.formatters.text import _format_feature, _SPACE
label_desc: Use image node_id 3 for calling a global function with example usage: test_format_unhashed_feature() without return types