input: Write a python function to search for a keyword in a list of strings.
  assert keyword_search(['apple', 'banana', 'cherry', 'date'], 'banana')==True
  assert keyword_search(['apple', 'banana', 'cherry', 'date'], 'fig')==False
  assert keyword_search(['dog', 'cat', 'bird', 'fish'], 'cat')==True
  assert keyword_search(['dog', 'cat', 'bird', 'fish'], 'horse')==False
output: def keyword_search(strings, keyword):
      return keyword in strings