input: Write a function to check if the given string contains the word "Hello". If it does, return True, otherwise return False.
  assert check_hello("Hello world")==True
  assert check_hello("Hi there")==False
  assert check_hello("A big Hello to everyone")==True
  assert check_hello("Programming is fun")==False
  assert check_hello("")==False
output: def check_hello(s):
      return "Hello" in s