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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 voxelwise_diff(img_spec1=None, img_spec2=None, abs_value=True, cmap='gray', overlay_image=False, overlay_alpha=0.8, num_rows=2, num_cols=6, rescale_method='global', background_threshold=0.05, annot=None, padding=5, output_path=None, figsize=None):
 """ Voxel-wise difference map. Parameters img_spec1 : str or nibabel image-like object MR image (or path to one) to be visualized img_spec2 : str or nibabel image-like object MR image (or path to one) to be visualized abs_value : bool Flag indicating whether to take the absolute value of the diffenence or not. Default: True, display absolute differences only (so order of images does not matter) Colormap to show the difference values. overlay_image : bool Flag to specify whether to overlay the difference values on the original image. .. note: This feature is not reliable and supported well yet. num_rows : int number of rows (top to bottom) per each of 3 dimensions num_cols : int number of panels (left to right) per row of each dimension. rescale_method : bool or str or list or None Range to rescale the intensity values to Default: 'global', min and max values computed based on ranges from both images. If false or None, no rescaling is done (does not work yet). background_threshold : float or str A threshold value below which all the background voxels will be set to zero. Default : 0.05. Other option is a string specifying a percentile: '5%', '10%'. Specify None if you don't want any thresholding. annot : str Text to display to annotate the visualization padding : int number of voxels to pad around each panel. output_path : str path to save the generate collage to. figsize : list Size of figure in inches to be passed on to plt.figure() e.g. [12, 12] or [20, 20] Returns ------- fig : figure handle handle to the collage figure generated. """


    if not isinstance(abs_value, bool):
        abs_value = bool(abs_value)

    mixer_params = dict(abs_value=abs_value,
                        cmap=cmap,
                        overlay_image=overlay_image,
                        overlay_alpha=overlay_alpha)
    fig = _compare(img_spec1,
                   img_spec2,
                   num_rows=num_rows,
                   num_cols=num_cols,
                   mixer='voxelwise_diff',
                   annot=annot,
                   padding=padding,
                   rescale_method=rescale_method,
                   bkground_thresh=background_threshold,
                   output_path=output_path,
                   figsize=figsize,
                   **mixer_params)

    return fig