code: def test_edge_type_str():
      edge_type_str = EdgeTypeStr("a__links__b")
      assert isinstance(edge_type_str, str)
      assert edge_type_str == "a__links__b"
      assert edge_type_str.to_tuple() == ("a", "links", "b")
  
      edge_type_str = EdgeTypeStr("a", "b")
      assert isinstance(edge_type_str, str)
      assert edge_type_str == "a__to__b"
      assert edge_type_str.to_tuple() == ("a", "to", "b")
  
      edge_type_str = EdgeTypeStr(("a", "b"))
      assert isinstance(edge_type_str, str)
      assert edge_type_str == "a__to__b"
      assert edge_type_str.to_tuple() == ("a", "to", "b")
  
      edge_type_str = EdgeTypeStr("a", "links", "b")
      assert isinstance(edge_type_str, str)
      assert edge_type_str == "a__links__b"
      assert edge_type_str.to_tuple() == ("a", "links", "b")
  
      edge_type_str = EdgeTypeStr(("a", "links", "b"))
      assert isinstance(edge_type_str, str)
      assert edge_type_str == "a__links__b"
      assert edge_type_str.to_tuple() == ("a", "links", "b")
  
      with pytest.raises(ValueError, match="invalid edge type"):
          EdgeTypeStr("a", "b", "c", "d")
  
      with pytest.raises(
          ValueError, match="Cannot convert the edge type"
      ):
          EdgeTypeStr("a__b__c__d").to_tuple()
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_edge_type_str() without return types