[Feature] Can `process` command be introduced in templates

Can process command be introduced in templates such that text can be piped into and from it like

f() | process(...).out | process(..., format="<output format parser like say JSON>").out | g()`

process will create a process to which one can pipe data into stdin. Also maybe this can be enabled and disabled in the config.

This will be like load_data but data is returned from a process. Alternatively, it can be load_data(exec="...").out

We have thought about something similar-ish but it’s not planned for now.