input: Write a python function to print a given string a specified number of times.
  assert print_string_n_times(3, "Hello")=="Hello\nHello\nHello\n"
  assert print_string_n_times(5, "Python")=="Python\nPython\nPython\nPython\nPython\n"
  assert print_string_n_times(2, "Test")=="Test\nTest\n"
output: def print_string_n_times(n, s):
      return (s + '\n') * n