code: def testLambdaToRef(self):
      self._testNonSearchSpaceRef(lambda x: x)
  
imports: import numpy
  import unittest
  from ray import tune
  from ray.tune.impl.placeholder import inject_placeholders, resolve_placeholders, create_resolvers_map, _FunctionResolver, _RefResolver
  from ray.tune.search.sample import Float, Integer
label_desc: Use image node_id 6 for calling the PlaceholderTest obj's underlying member method code with example usage: obj.testLambdaToRef() without return types