input: Write a python function to check if specific output files are created.
  assert check_files_created(['stack_rate', 'stack_error', 'linear_rate', 'linear_error', 'linear_rsquared'], '.tif', 'path_to_output')==True
  assert check_files_created(['stack_rate', 'stack_error'], '.png', 'another_path_to_output')==True
  assert check_files_created(['linear_rate'], '.kml', 'yet_another_path_to_output')==False
output: def check_files_created(file_names, extension, directory):
      import os
      return all(os.path.isfile(os.path.join(directory, f"{name}{extension}")) for name in file_names)