If non-nil, shared substructures anywhere in the structure are printed
with `#N=' before the first occurrence (in the order of the print
representation) and `#N#' in place of each subsequent occurrence,
-where N is a positive decimal integer.
-
-There is no way to read this representation in standard Emacs,
-but if you need to do so, try the cl-read.el package."
+where N is a positive decimal integer."
:type 'boolean
:group 'cust-print)