library(printlength) provides four predicates to determine how wide a
term would be if written:
print_length/2allows you to determine how many columns an atom (or other term) would take if printed according to Command. The length of the output of any command at all can be determined this way, provided that it writes to the current stream, and not to a stream argument.
print_length/2fails if Command fails.
line_positionas "the number of characters that have already been read from/written on this line"), so
print_length/3will fail if StartColumn is negative.
print_length/3fails if Command fails.
)is true by writing 0 or 1 newlines and at most Column spaces to the Current_output stream.