'Write image to file FILENAME in FORMAT starting from
position FROM_COORDS.'

def write(self, filename, format=None, from_coords=None):

    args = (self.name, 'write', filename)
    if format:
        args = (args + ('-format', format))
    if from_coords:
        args = ((args + ('-from',)) + tuple(from_coords))
    self.tk.call(args)
