code: def test_check_derived_table_alias_map(self):
      # key exists
      ctx = StatementBinderContext(MagicMock())
      obj1 = MagicMock()
      obj2 = MagicMock()
      col_map = {"col1": obj1, "col2": obj2}
      ctx._derived_table_alias_map["alias"] = col_map
      result = ctx._check_derived_table_alias_map("alias", "col1")
      self.assertEqual(result, obj1)
      result = ctx._check_derived_table_alias_map("alias", "col2")
      self.assertEqual(result, obj2)
  
      # key does not exist
      ctx = StatementBinderContext(MagicMock())
      result = ctx._check_derived_table_alias_map("alias", "col3")
      self.assertEqual(result, None)
  
imports: import unittest
  from unittest.mock import MagicMock
  import pytest
  from evadb.binder.binder_utils import BinderError
  from evadb.binder.statement_binder_context import StatementBinderContext
  from evadb.expression.function_expression import FunctionExpression
  from evadb.expression.tuple_value_expression import TupleValueExpression
label_desc: Use image node_id 10 for calling the StatementBinderTests obj's underlying member method code with example usage: obj.test_check_derived_table_alias_map() without return types