input: Write a function to return True if the given string `s` contains the word "Hello", otherwise return False.
  
  def check_hello(s):
      return 'Hello' in s
  
  assert check_hello("Hello, world!")==True
  assert check_hello("Hi there!")==False
  assert check_hello("Hello there, how are you?")==True
  assert check_hello("")==False
output: def check_hello(s):
      return 'Hello' in s