code: def test_basic(self):
      def f(n):
          a = 0
          b = 0
          if n > 0:
              a = -n
          else:
              b = 2 * n
          return a, b
  
      self.assertTransformedResult(f, custom_constant(1), (-1, 0))
      self.assertTransformedResult(f, custom_constant(-1), (0, -2))
  
imports: import collections
  from nvidia.dali._autograph.converters import break_statements
  from nvidia.dali._autograph.converters import continue_statements
  from nvidia.dali._autograph.converters import control_flow
  from nvidia.dali._autograph.core import converter_testing
  from nvidia.dali._autograph.utils.all_utils import custom_constant
label_desc: Use image node_id 1 for calling the IfStatementTest obj's underlying member method code with example usage: obj.test_basic() and returns: a,  b