Avisynth does not support eg 5 pairs of quotes (so as to be able to enclose both triple and single quotes), which can make things awkward.
(Other languages eg BASIC allow for 5 pairs [EDIT: and maybe 7 pairs of double] quotes [methinks]).
Code:
SSS="""
Subtitle("Current frame = " + String(current_frame), align=5)
"""
Scriptclip(SSS)
So can use as above, for use with your MP_Pipeline thing.
EDIT: Not sure how you use the mp_pipeline thing, maybe something like so
Code:
SSS="""
Subtitle("Current frame = " + String(current_frame), align=5)
"""
mp_pipeline("Scriptclip(SSS)")
EDIT: I sometimes use the Multi-Instance template model developed by Gavino and Martin53, to get around the missing 5 pairs of double quotes thing.
EDIT: And the SSS= """ ... """ thing is nothing to do with the 'ssS' on the end of my username, I usually use to signify a triple quoted string,
although some times as 'main source string' where S used for a substring of it.