The value of this object indicates the script's execution
state. If the script has been invoked but has not yet
begun execution, the value will be `initializing'. If the
script is running, the value will be `executing'.
A running script which received a request to suspend
execution first transitions into a temporary `suspending'
state. The temporary `suspending' state changes to
`suspended' when the script has actually been suspended. The
temporary `suspending' state changes back to `executing' if
the attempt to suspend the running script fails.
A suspended script which received a request to resume
execution first transitions into a temporary `resuming'
state. The temporary `resuming' state changes to `running'
when the script has actually been resumed. The temporary
`resuming' state changes back to `suspended' if the attempt
to resume the suspended script fails.
A script which received a request to abort execution but
which is still running first transitions into a temporary
`aborting' state.
A script which has finished its execution is `terminated'.