input: def binary_classification_model(X, y) -> float:
      """Implement a basic machine learning model that performs binary classification on the given data.
      The model uses logistic regression from scikit-learn.
      
      >>> X = [[0.3, 0.2, 0.6], [0.3, 0.1, 0.4], [0.2, 0.3, 0.4], [0.7, 0.4, 0.2], [0.5, 0.2, 0.1]]
      >>> y = [1, 0, 0, 1, 0]
      >>> binary_classification_model(X, y)
      'Model accuracy: 1.0'
      """
      from sklearn import linear_model
      from sklearn.metrics import accuracy_score
  
      model = linear_model.LogisticRegression()
      model.fit(X, y)
  
      y_pred = model.predict(X)
      accuracy = accuracy_score(y, y_pred)
  
      return f'Model accuracy: {accuracy}'
output:     from sklearn import linear_model
      from sklearn.metrics import accuracy_score
  
      model = linear_model.LogisticRegression()
      model.fit(X, y)
  
      y_pred = model.predict(X)
      accuracy = accuracy_score(y, y_pred)
  
      return f'Model accuracy: {accuracy}'