input: Write a python function to create a classification model using random forests.
  assert isinstance(random_forest_classifier([[1, 2], [3, 4]], [0, 1]), RandomForestClassifier)
  assert random_forest_classifier([[5, 6], [7, 8]], [1, 0]).random_state == 42
output: def random_forest_classifier(X, y):
      from sklearn.ensemble import RandomForestClassifier
      model = RandomForestClassifier(random_state=42)
      model.fit(X, y)
      return model