input: Write a function that takes two strings and returns True if the first string contains the second, and False otherwise.
  
  assert check_contains("catering", "cat") == True
  assert check_contains("application", "app") == True
  assert check_contains("python", "jython") == False
  assert check_contains("programming", "gram") == True
  assert check_contains("", "empty") == False
output: def check_contains(s1, s2):
      return s2 in s1