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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 connectSubsystem(connection, protocol, subsystem):
 """Connect a Protocol to a ssh subsystem channel """

    deferred = connectSession(connection, protocol)
    @deferred.addCallback
    def requestSubsystem(session):
        return session.requestSubsystem(subsystem)
    return deferred