pprint - pretty print: Print object to a stream
ostream any <- -> ostream
cerr [1 2 3] pprint endl ; -> [1 2 3]
Alternatives: You can use <-- (undocumented),
which is the same as pprint.
docu by Marc Oliver Gewaltig and Sirko Straube
/var/www/debian/nest/nest-simulator-2.20.0/sli/sli_io.cc