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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 find_executable(executable, path=None):
 """ As distutils.spawn.find_executable, but on Windows, look up every extension declared in PATHEXT instead of just `.exe` """

    if sys.platform != 'win32':
        return distutils.spawn.find_executable(executable, path)

    if path is None:
        path = os.environ['PATH']

    paths = path.split(os.pathsep)
    extensions = os.environ.get('PATHEXT', '.exe').split(os.pathsep)
    base, ext = os.path.splitext(executable)

    if not os.path.isfile(executable):
        for p in paths:
            for ext in extensions:
                f = os.path.join(p, base + ext)
                if os.path.isfile(f):
                    return f
        return None
    else:
        return executable