input: Write a function that will take two strings and return true if the first string contains the second.
  assert check_contains("catering", "cat")==True
  assert check_contains("basketball", "ball")==True
  assert check_contains("moonlight", "sun")==False
  assert check_contains("developer", "dev")==True
  assert check_contains("", "empty")==False
output: def check_contains(s1, s2):
      return s2 in s1