input: Write a python function to count the total number of words in a list of sentences.
  assert count_words(["Hello world", "Python is great", "I love coding"]) == 7
  assert count_words(["The quick brown fox", "jumps over the lazy dog"]) == 9
  assert count_words(["This is a test", "Another test", "And another one"]) == 8
output: def count_words(sentences):
      return sum(len(sentence.split()) for sentence in sentences)