code: def test_unknown_data_type(self, schema):
      schema = {"new": "unknown"}
      with pytest.raises(ValueError, match="Unknown data type"):
          validate_schema(nodes={"new"}, schema=schema)
  
imports: from collections import OrderedDict
  import pytest
  from causalnex.structure import StructureModel
  from causalnex.structure.categorical_variable_mapper import VariableFeatureMapper, validate_schema
label_desc: Use image node_id 1 for calling the TestValidateSchema obj's underlying member method code with example usage: obj.test_unknown_data_type(schema) without return types