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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 identify_module(arg):
 """Import and return the Python module named in `arg`. If the module cannot be imported, a `pywhich.ModuleNotFound` exception is raised. """

    try:
        __import__(arg)
    except Exception:
        exc = sys.exc_info()[1]
        raise ModuleNotFound("%s: %s" % (type(exc).__name__, str(exc)))

    mod = sys.modules[arg]
    return mod