input: def replace_word_in_sentence(sentence: str, old_word: str, new_word: str) -> str:
      """ Replace a given word in a sentence with another word.
      >>> replace_word_in_sentence("I love walking on the beach", "walking", "swimming")
      'The new sentence is: \'I love swimming on the beach\''
      """
output:     words = sentence.split()
      for i in range(len(words)):
          if words[i] == old_word:
              words[i] = new_word
      new_sentence = ' '.join(words)
      return f'The new sentence is: \'{new_sentence}\''