input: Write a function to determine if a given string contains the word "Hello". If it does, return True; otherwise, return False.
  def check_hello(s):
      return 'Hello' in s
  assert check_hello("Hello, world!")==True
  assert check_hello("Goodbye, world.")==False
  assert check_hello("HelloHello")==True
  assert check_hello("hello")==False
  assert check_hello("")==False
output: def check_hello(s):
      return 'Hello' in s