input: Write a python function to filter countries with population greater than 500 million.
  assert filter_countries(DATA_LIST)==["China", "India"]
  assert filter_countries([("United States", 321107000,  "North America"), ("Indonesia", 255461700,  "Asia")])==[]
  assert filter_countries([("China", 1370130000, "Asia"), ("India", 1271980000, "Asia"), ("Nigeria", 183523000, "Africa")])==["China", "India"]
output: def filter_countries(data_list):
      return [country for country, population, continent in data_list if population > 500_000_000]