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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 display_image_file(fn, width='auto', height='auto', preserve_aspect_ratio=None):
 """ Display an image in the terminal. A newline is not printed. width and height are strings, following the format N: N character cells. Npx: N pixels. N%: N percent of the session's width or height. 'auto': The image's inherent size will be used to determine an appropriate dimension. preserve_aspect_ratio sets whether the aspect ratio of the image is preserved. The default (None) is True unless both width and height are set. See https://www.iterm2.com/documentation-images.html """

    with open(os.path.realpath(os.path.expanduser(fn)), 'rb') as f:
        sys.stdout.buffer.write(image_bytes(f.read(), filename=fn,
            width=width, height=height,
            preserve_aspect_ratio=preserve_aspect_ratio))