How to use the pypuppetdb.QueryBuilder.ExtractOperator function in pypuppetdb

def test_events_endpoint(self):
        assert str(InOperator('certname')) == \
            '["in", "certname"]'

        op = InOperator('certname')
        ex = ExtractOperator()
        ex.add_field("certname")
        op.add_query(ex)

        assert repr(op) == 'Query: ["in", "certname", ' \
            '["extract", ["certname"]]]'

ex = ExtractOperator()
        ex.add_field(["certname", "facts"])
        fr = FromOperator("facts")
        fr.add_query(ex)
        fr.add_offset(10)
        op.add_query(fr)

        assert repr(op) == 'Query: ["in", "certname", ' \
            '["from", "facts", ["extract", ' \
            '["certname", "facts"]], ["offset", 10]]]'

        # last example on page
        # https://puppet.com/docs/puppetdb/5.1/api/query/v4/ast.html

        op = InOperator('certname')
        ex = ExtractOperator()
        ex.add_field('certname')
        fr = FromOperator('fact_contents')
        nd = AndOperator()
        nd.add(EqualsOperator("path",
                              ["networking", "eth0", "macaddresses", 0]))
        nd.add(EqualsOperator("value", "aa:bb:cc:dd:ee:00"))
        ex.add_query(nd)
        fr.add_query(ex)
        op.add_query(fr)

        assert str(op) == '["in", "certname", ' \
                          '["from", "fact_contents", ' \

def test_with_add_function_operator(self):
        op = ExtractOperator()

        op.add_field(FunctionOperator('to_string',
                                      'producer_timestamp',
                                      'FMDAY'))
        op.add_field(FunctionOperator('count'))
        op.add_group_by(FunctionOperator('to_string',
                                         'producer_timestamp',
                                         'FMDAY'))

        assert str(op) == '["extract", '\
            '[["function", "to_string", "producer_timestamp", "FMDAY"], '\
            '["function", "count"]], '\
            '["group_by", '\
            '["function", "to_string", "producer_timestamp", "FMDAY"]]]'
        assert repr(op) == 'Query: ["extract", '\
            '[["function", "to_string", "producer_timestamp", "FMDAY"], '\

def test_multiple_add_query(self):
        with pytest.raises(APIError):
            op = InOperator('certname')
            op.add_query(ExtractOperator())
            op.add_query(ExtractOperator())

def test_with_add_field(self):
        op = ExtractOperator()

        with pytest.raises(APIError):
            repr(op)
        with pytest.raises(APIError):
            str(op)
        with pytest.raises(APIError):
            str(op)

        op.add_field("certname")
        op.add_field(['fact_environment', 'catalog_environment'])

        assert repr(op) == 'Query: ["extract", '\
            '["certname", "fact_environment", "catalog_environment"]]'
        assert str(op) == '["extract", '\
            '["certname", "fact_environment", "catalog_environment"]]'
        assert str(op) == '["extract", ' \

op.add_array(inv1)

        with pytest.raises(APIError):
            op = InOperator('certname')
            op.add_array(inv2)

        with pytest.raises(APIError):
            op = InOperator('certname')
            op.add_array(arr)
            op.add_array(arr)

        with pytest.raises(APIError):
            op = InOperator('certname')

            op.add_array(arr)
            ex = ExtractOperator()
            ex.add_field("certname")
            op.add_query(ex)

fr = FromOperator("facts")
        op = EqualsOperator("certname", "test01")
        fr.add_query(op)

        assert str(fr) == '["from", "facts", ["=", "certname", "test01"]]'

        fr2 = FromOperator("facts")
        op2 = "test, test, test"
        with pytest.raises(APIError):
            fr2.add_query(op2)
        fr2.add_query(op)
        with pytest.raises(APIError):
            fr2.add_query(op)

        fr3 = FromOperator("facts")
        op3 = ExtractOperator()
        op3.add_field(['certname', 'fact_environment', 'catalog_environment'])
        fr3.add_query(op3)

        assert str(fr3) == \
            '["from", "facts", ["extract", '\
            '["certname", "fact_environment", "catalog_environment"]]]'

def test_fromoperator(self):
        op = InOperator('certname')
        ex = ExtractOperator()
        ex.add_field(["certname", "facts"])
        fr = FromOperator("facts")
        fr.add_query(ex)
        fr.add_offset(10)
        op.add_query(fr)

        assert repr(op) == 'Query: ["in", "certname", ' \
            '["from", "facts", ["extract", ' \
            '["certname", "facts"]], ["offset", 10]]]'

        # last example on page
        # https://puppet.com/docs/puppetdb/5.1/api/query/v4/ast.html

        op = InOperator('certname')
        ex = ExtractOperator()
        ex.add_field('certname')

def test_with_add_query(self):
        op = ExtractOperator()

        op.add_field(['certname', 'fact_environment', 'catalog_environment'])

        with pytest.raises(APIError):
            op.add_query({'less': 42, 'greater': 50})

        op.add_query(EqualsOperator('domain', 'example.com'))

        assert repr(op) == 'Query: ["extract", '\
            '["certname", "fact_environment", "catalog_environment"], '\
            '["=", "domain", "example.com"]]'
        assert str(op) == '["extract", '\
            '["certname", "fact_environment", "catalog_environment"], '\
            '["=", "domain", "example.com"]]'
        assert str(op) == '["extract", ' \
                          '["certname", "fact_environment", "catalog_environment"], '\