input: Write a function to identify the longest word in a given sentence. If multiple words have the same length and are the longest, return the first one encountered.
  assert find_longest_word("The rain in Spain stays mainly in the plain.") == "mainly"
  assert find_longest_word("I love programming") == "programming"
  assert find_longest_word("Python is fun") == "Python"
  assert find_longest_word("Coding is cool") == "Coding"
  assert find_longest_word("Oneword") == "Oneword"
output: def find_longest_word(sentence):
      words = sentence.split()
      longest_word = ""
      for word in words:
          if len(word) > len(longest_word):
              longest_word = word
      return longest_word