input: Write a function to create a Python script that enters a Kaggle competition by loading necessary libraries, reading in data, preprocessing it, splitting it into training and testing sets, defining and fitting a model, making predictions, scoring the predictions, and potentially submitting the results to Kaggle. If no model is defined, return "No model defined". If the prediction score is greater than 0.8, return "High accuracy". If the prediction score is between 0.5 and 0.8, return "Moderate accuracy". If the prediction score is less than 0.5, return "Low accuracy".
  assert kaggle_competition()== "No model defined"
  assert kaggle_competition()== "High accuracy"
  assert kaggle_competition()== "Moderate accuracy"
  assert kaggle_competition()== "Low accuracy"
output: def kaggle_competition():
      # Placeholder for model definition
      model = None
      
      if model is None:
          return "No model defined"
      
      # Placeholder for prediction score
      prediction_score = 0.9
      
      if prediction_score > 0.8:
          return "High accuracy"
      elif prediction_score >= 0.5:
          return "Moderate accuracy"
      else:
          return "Low accuracy"