def read_output(filename):
    if os.path.isfile(filename):
        with open(filename, 'rb') as f:
            return f.read().decode('utf-8')
    elif os.path.isfile('{}.gz'.format(filename)):
        with gzip.open('{}.gz'.format(filename), 'rb') as f:
            return f.read().decode('utf-8')
    elif HAS_LZMA and os.path.isfile('{}.xz'.format(filename)):
        with open('{}.xz'.format(filename), 'rb') as f:
            return lzma.LZMADecompressor().decompress(f.read()).decode('utf-8')
    else:
        return None