environment/lib/python2.7/site-packages/IPython/nbformat/v3/rwbase.py
def base64_decode(nb):
    """Restore all bytes objects in the notebook from base64-encoded strings.
    
    Note: This is never used
    """
    for ws in nb.worksheets:
        for cell in ws.cells:
            if cell.cell_type == 'code':
                for output in cell.outputs:
                    if 'png' in output:
                        if isinstance(output.png, unicode):
                            output.png = output.png.encode('ascii')
                        output.png = decodestring(output.png)
                    if 'jpeg' in output:
                        if isinstance(output.jpeg, unicode):
                            output.jpeg = output.jpeg.encode('ascii')
                        output.jpeg = decodestring(output.jpeg)
    return nb
def base64_decode(nb):
    """Restore all bytes objects in the notebook from base64-encoded strings.
    
    Note: This is never used
    """
    for ws in nb.worksheets:
        for cell in ws.cells:
            if cell.cell_type == 'code':
                for output in cell.outputs:
                    if 'png' in output:
                        if isinstance(output.png, unicode):
                            output.png = output.png.encode('ascii')
                        output.png = decodestring(output.png)
                    if 'jpeg' in output:
                        if isinstance(output.jpeg, unicode):
                            output.jpeg = output.jpeg.encode('ascii')
                        output.jpeg = decodestring(output.jpeg)
    return nb
Restore all bytes objects in the notebook from base64-encoded strings.
    
    Note: This is never used