input: Write a python function to classify documents based on word counts.
  assert classify_document("The match was intense and the players showed great skill") == "sports"
  assert classify_document("The new policy will impact the economy") == "politics"
  assert classify_document("The stock market saw significant growth today") == "business"
  assert classify_document("The government announced new regulations for businesses") == "politics"
output: def classify_document(document):
      sports_keywords = {"match", "players", "skill", "team", "tournament", "game", "score"}
      politics_keywords = {"policy", "government", "election", "regulations", "campaign"}
      business_keywords = {"economy", "market", "stock", "businesses", "growth", "trade"}
  
      words = set(document.lower().split())
  
      if words & sports_keywords:
          return "sports"
      elif words & politics_keywords:
          return "politics"
      elif words & business_keywords:
          return "business"
      else:
          return "unknown"