input: Write a function to take a sentence as input and return a list of verbs extracted from the sentence using the NLTK library. Use the pos_tag function to determine the parts of speech. If the input sentence is empty, return an empty list.
  
  assert extract_verbs("The cat jumped over the moon.")==['jumped']
  assert extract_verbs("She is running fast.")==['is', 'running']
  assert extract_verbs("He eats an apple.")==['eats']
  assert extract_verbs("They played the entire night.")==['played', 'night']
  assert extract_verbs("")==[]
output: def extract_verbs(sentence):
      if not sentence:
          return []
      from nltk import pos_tag, word_tokenize
      words = word_tokenize(sentence)
      tagged = pos_tag(words)
      verbs = [word for word, pos in tagged if pos.startswith('VB')]
      return verbs