docs: def precision(y, y_pred):
      """Precision score
  
      precision = true_positives / (true_positives + false_positives)
      
      Parameters:
      -----------
      y : vector, shape (n_samples,)
      The target labels.
  
      y_pred : vector, shape (n_samples,)
      The predicted labels.
      
      Returns:
      --------
      precision : float
      
      """
  
      tp = true_positives(y, y_pred)
      fp = false_positives(y, y_pred)
      return  tp / (tp + fp)