code: def test_no_cast_nulls(self):
      values = ("", "N/A", None)
  
      t = Text()
      casted = tuple(t.cast(v) for v in values)
      self.assertSequenceEqual(casted, (None, None, None))
  
      t = Text(cast_nulls=False)
      casted = tuple(t.cast(v) for v in values)
      self.assertSequenceEqual(casted, ("", "N/A", None))
  
imports: import datetime
  import pickle
  import unittest
  from decimal import Decimal
  import parsedatetime
  from agate.data_types import Boolean, Date, DateTime, Number, Text, TimeDelta
  from agate.exceptions import CastError
label_desc: Use image node_id 4 for calling the TestText obj's underlying member method code with example usage: obj.test_no_cast_nulls() without return types