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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def extract_pixels(X):
 """ Extract pixels from array X :param X: Array of images to be classified. :type X: numpy array, shape = [n_images, n_pixels_y, n_pixels_x, n_bands] :return: Reshaped 2D array :rtype: numpy array, [n_samples*n_pixels_y*n_pixels_x,n_bands] :raises: ValueError is input array has wrong dimensions """

        if len(X.shape) != 4:
            raise ValueError('Array of input images has to be a 4-dimensional array of shape'
                             '[n_images, n_pixels_y, n_pixels_x, n_bands]')

        new_shape = (X.shape[0] * X.shape[1] * X.shape[2], X.shape[3],)
        pixels = X.reshape(new_shape)
        return pixels