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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 toplevel_packages():
 """ Get package list, without sub-packages. """

    packages = set(easy.options.setup.packages)
    for pkg in list(packages):
        packages -= set(p for p in packages if str(p).startswith(pkg + '.'))
    return list(sorted(packages))