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