.z.pg (port get)
When .z.pg is set, it is called with the object that is passed to this kdb+ session via a synchronous request. The return value, if any, is returned to the calling task.
.z.pg can be unset with \x .z.pg, which restores the default behavior.
The default behavior is equivalent to setting .z.pg to value and executes in the root context.
For a complete list of functions, see the kdb+ Function Reference.