format the standard list application form. example (append a b)

parses a string and removes outside string indent from using newlines in a continuous string that is indented.
adds current indent to all lines except the first.
since old-indent is not available here, old-indent is guessed from the second line.
if the second line is indented relative to the first line, this indent will unfortunately be removed for all lines

helper that customises config start/middle/end

format-f that formats a list with the given start/mid/end expression distribution

join expressions eventually with empty lines inbetween them