input: Write a function to check if a given string contains the word "Hello". If the word "Hello" is found in the string, return True, otherwise return False.
  assert check_hello("Hello, world!")==True
  assert check_hello("Hi there!")==False
  assert check_hello("Say Hello to everyone.")==True
  assert check_hello("")==False
  assert check_hello("Pleased to meet you.")==False
output: def check_hello(s):
      return "Hello" in s