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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 check_archive_filelist (filenames):
 """Check that file list is not empty and contains only existing files."""

    if not filenames:
        raise PatoolError("cannot create archive with empty filelist")
    for filename in filenames:
        check_existing_filename(filename, onlyfiles=False)