In various embodiments, {HEAD ~ user system} 100 comprises {TAIL ~ one or more physical systems} with one or more processors, one or more memories, and one or more other storage devices and one or more virtual environments in which a user application is executed 
In various embodiments , { HEAD ~ user system } 100 comprises { TAIL ~ one or more physical systems } with one or more processors , one or more memories , and one or more other storage devices and one or more virtual environments in which a user application is executed
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