code: def testMergeDescriptorSingleReal(self):
      p1 = Pool()
      p1.set("real", 1)
      p2 = Pool()
      p2.set("real", 2)
      # single value descriptors only allow for replace when merging data:
      self.assertRaises(
          EssentiaException, p1.mergeSingle, "real", p2["real"]
      )
      p1.mergeSingle("real", p2["real"], "replace")
      self.assertEqual(p1["real"], p2["real"])
  
imports: from essentia_test import *
label_desc: Use image node_id 33 for calling the TestPool obj's underlying member method code with example usage: obj.testMergeDescriptorSingleReal() without return types