code: def test_n_features_len(self, mapper, schema):
      assert mapper.n_features == sum(
          (int(v.split(":")[1]) if "categorical" in v else 1)
          for v in schema.values()
      )
  
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 11 for calling the TestVariableFeatureMapper obj's underlying member method code with example usage: obj.test_n_features_len(mapper, schema) without return types