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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 list_backends():
 """Return installed backends. Backends are installed python packages named pyvisa-<something> where <something> is the name of the backend. :rtype: list """

    return ['ni'] + [name for (loader, name, ispkg) in pkgutil.iter_modules()
                     if name.startswith('pyvisa-') and not name.endswith('-script')]