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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 pretty_filename(filename):
    '''Returns a nice human readable path to 'filename'.'''
    try:
        a = os.path.abspath(filename)
        r = os.path.relpath(filename)
    except ValueError:
        # Catch relpath exception. Happens, because it can not produce relative path
        # if wroking directory is on different drive.
        a = r = filename
    return a if '..' in r else r