It'd be backwards compatible if it's only enabled by a specific string at the start of the script, e.g. #!multiline or something equally unlikely.
I was thinking more of individual calls with many parameters, which can't be broken up, but assigning to temp variables again and again for long strings of calls seems equally messy to me.
How much neater to be able to write like this and quickly comment out/rejoin single lines without having to worry about all the backslahes (which, I'd argue, only make it harder to read):
Code:
processed = source.
qtgmc.
flipvertical.
filter_with_many_parameters(
10,
20,
"mode", # you can even put a comment here if you want to
reverse = true
).
trim(50, 99).
selecteven;