def update_parameters(params, grads, learning_rate=0.001):
    
    """
    Update the parameters:
    W = W - lr*dW
    b = b - lr*db
    
    Arguments:
    W -- weights (num_of_features, 1)
    b -- scalar value
    dW, db -- gradients
    learning_rate -- the rate at which the params should update (default = 0.001)
    
    Returns:
    W, b -- updated parameters
    """
    
    params['W'] -= learning_rate*grads['dW']
    params['b'] -= learning_rate*grads['db']
    
    return params