code: def test_lambda_gc_nans(self):
      N = 5000000
      ht = hl.utils.range_table(N).annotate(
          x=hl.scan.count() / N, is_even=hl.scan.count() % 2 == 0
      )
      lgc_nan = hl.lambda_gc(
          hl.case().when(ht.is_even, hl.float("nan")).default(ht.x)
      )
      self.assertAlmostEqual(lgc_nan, 1, places=1)
  
imports: import unittest
  import hail
  from ..helpers import *
label_desc: Use image node_id 17 for calling the Tests obj's underlying member method code with example usage: obj.test_lambda_gc_nans() without return types