code: def test_define_function(self):
      f1 = hl.experimental.define_function(
          lambda a, b: (a + 7) * b, hl.tint32, hl.tint32
      )
      self.assertEqual(hl.eval(f1(1, 3)), 24)
      f2 = hl.experimental.define_function(
          lambda a, b: (a + 7) * b, hl.tint32, hl.tint32
      )
      self.assertEqual(hl.eval(f1(1, 3)), 24)  # idempotent
      self.assertEqual(hl.eval(f2(1, 3)), 24)
  
imports: import numpy
  import hail
  import unittest
  import pytest
  from ..helpers import *
  from hail.utils import new_temp_file
label_desc: Use image node_id 11 for calling the Tests obj's underlying member method code with example usage: obj.test_define_function() without return types