text: import unittest
  from etk.knowledge_graph.graph import Graph
  from etk.knowledge_graph.schema import KGSchema
  from etk.knowledge_graph.subject import Subject
  from etk.knowledge_graph.node import URI, BNode, Literal, LiteralType
  
  
  MASTER_CONFIG_EXAMPLE = '''
  {
      "fields": {
          "cameo_code": {
              "type": "string", 
              "description": "CAMEO code to describe the type of event in the ICEWS dataset"
          }, 
          "answer_option": {
              "type": "kg_id" 
          }, 
          "reference": {
              "type": "string"
          }
      }
  }
  '''
  
  Ontology_EXAMPLE = '''
  @prefix : <http://dig.isi.edu/ontologies/dig/> .
  @prefix owl: <http://www.w3.org/2002/07/owl#> .
  @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
  @prefix skos: <http://www.w3.org/2004/02/skos/core#> .
  :Entity a owl:Class ;
      rdfs:label "Entity" ;
      skos:definition """Everything that can be described, similar to owl:Thing.""" ;
      :common_properties :label, :title, :description ; .
  '''
  
  
  class TestKGSchema(unittest.TestCase):
      def test_kg_schema(self):
          schema = KGSchema()
          schema.add_schema(Ontology_EXAMPLE, 'ttl')
  
      def test_kg_schema_master_config(self):
          schema = KGSchema()
          schema.add_schema(MASTER_CONFIG_EXAMPLE, 'master_config')
          self.assertEqual(len(schema.fields), 3)
  