input: Write a function to check if the first string contains the second string. Return True if the first string contains the second string, otherwise return False.
  
  assert check_contains("catering", "cat")==True
  assert check_contains("elephant", "ant")==True
  assert check_contains("zebra", "rabbit")==False
  assert check_contains("python", "on")==True
  assert check_contains("hello", "")==True
output: def check_contains(s1, s2):
      return s2 in s1