code: def test_and_(self):
      expr1 = self.gen_cmp_expr(10)
      expr2 = self.gen_cmp_expr(20)
      new_expr = conjunction_list_to_expression_tree([expr1, expr2])
      self.assertEqual(new_expr.etype, ExpressionType.LOGICAL_AND)
      self.assertEqual(new_expr.children[0], expr1)
      self.assertEqual(new_expr.children[1], expr2)
  
file_path: evadb/test/unit_tests/expression/test_expression_utils.py
imports: import unittest
  from unittest.mock import Mock
  from evadb.expression.abstract_expression import ExpressionType
  from evadb.expression.arithmetic_expression import ArithmeticExpression
  from evadb.expression.comparison_expression import ComparisonExpression
  from evadb.expression.constant_value_expression import ConstantValueExpression
  from evadb.expression.expression_utils import conjunction_list_to_expression_tree, contains_single_column, extract_range_list_from_comparison_expr, extract_range_list_from_predicate, is_simple_predicate
  from evadb.expression.logical_expression import LogicalExpression
  from evadb.expression.tuple_value_expression import TupleValueExpression
label_desc: Use image node_id 6 for calling the ExpressionUtilsTest obj's underlying member method code with example usage: obj.test_and_() without return types