code: def test_fields_work_correctly(self):
      mt = self.get_groupable_matrix()
      a = mt.group_rows_by(mt["group1"]).aggregate(
          c=hl.agg.sum(mt["c"])
      )
      self.assertEqual(a.count_rows(), 6)
      self.assertTrue("group1" in a.row_key)
  
      b = mt.group_cols_by(mt["group3"]).aggregate(
          c=hl.agg.sum(mt["c"])
      )
      self.assertEqual(b.count_cols(), 6)
      self.assertTrue("group3" in b.col_key)
  
file_path: hail/hail/python/test/hail/matrixtable/test_grouped_matrix_table.py
imports: import unittest
  import hail
  from ..helpers import *
label_desc: Use image node_id 4 for calling the Tests obj's underlying member method code with example usage: obj.test_fields_work_correctly() without return types