code: def test_field_accessor(self):
      df = self.spark.createDataFrame(
          [Row(l=[1], r=Row(a=1, b="b"), d={"k": "v"})]
      )
      self.assertEqual(1, df.select(df.l[0]).first()[0])
      self.assertEqual(1, df.select(df.r["a"]).first()[0])
      self.assertEqual(1, df.select(df["r.a"]).first()[0])
      self.assertEqual("b", df.select(df.r["b"]).first()[0])
      self.assertEqual("b", df.select(df["r.b"]).first()[0])
      self.assertEqual("v", df.select(df.d["k"]).first()[0])
  
imports: from itertools import chain
  from pyspark.sql import Column, Row
  from pyspark.sql import functions
  from pyspark.sql.types import StructType, StructField, LongType
  from pyspark.errors import AnalysisException, PySparkTypeError, PySparkValueError
  from pyspark.testing.sqlutils import ReusedSQLTestCase
label_desc: Use image node_id 9 for calling the ColumnTestsMixin obj's underlying member method code with example usage: obj.test_field_accessor() without return types