input: Write a python function to find the largest word in a sentence.
  assert find_largest_word("This sentence has seven words.") == "sentence"
  assert find_largest_word("Write a python function to find the largest word.") == "function"
  assert find_largest_word("Short and long words in this sentence.") == "sentence"
output: def find_largest_word(sentence):
      words = sentence.split()
      largest_word = max(words, key=len)
      return largest_word