input: Write a python function to classify words in a sentence as positive or negative.
  assert classify_sentence("The weather is so gloomy today.") == ["negative"]
  assert classify_sentence("Life is wonderful and amazing!") == ["positive", "positive"]
  assert classify_sentence("I had a bad and sad day.") == ["negative", "negative"]
output: def classify_sentence(sentence):
      positive_words = {"wonderful", "amazing", "happy", "good", "great"}
      negative_words = {"bad", "sad", "gloomy", "terrible", "awful"}
      
      words = sentence.lower().split()
      classifications = []
      
      for word in words:
          if word in positive_words:
              classifications.append("positive")
          elif word in negative_words:
              classifications.append("negative")
      
      return classifications