/*REXX program  demonstrates  (with displays)  a method of  parametric polymorphism.    */
call newRoot  1.00, 3                            /*new root,  and also indicate 3 stems.*/
                                                 /* [↓]  no need to label the stems.    */
call addStem  1.10                               /*a new stem  and  its initial value.  */
call addStem  1.11                               /*"  "    "    "    "     "      "     */
call addStem  1.12                               /*"  "    "    "    "     "      "     */
call addStem  1.20                               /*"  "    "    "    "     "      "     */
call addStem  1.21                               /*"  "    "    "    "     "      "     */
call addStem  1.22                               /*"  "    "    "    "     "      "     */
                       call sayNodes             /*display some nicely formatted values.*/
call modRoot  50                                 /*modRoot will add fifty to all stems. */
                       call sayNodes             /*display some nicely formatted values.*/
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
addStem:  nodes=nodes + 1;     do j=1  for stems;   root.nodes.j=arg(1);   end;     return
newRoot:  parse arg @,stems; nodes=-1; call addStem copies('═',9); call addStem @;  return
/*──────────────────────────────────────────────────────────────────────────────────────*/
modRoot:  arg #;   do    j=1  for nodes          /*traipse through all the defined nodes*/
                      do k=1  for stems
                      if datatype(root.j.k,'N')  then root.j.k=root.j.k + #  /*add bias.*/
                      end   /*k*/                /* [↑]  only add if numeric stem value.*/
                   end      /*j*/
          return
/*──────────────────────────────────────────────────────────────────────────────────────*/
sayNodes: w=9;     do    j=0  to  nodes;   _=    /*ensure each of the nodes gets shown. */
                      do k=1  for stems;   _=_ center(root.j.k, w)  /*concatenate a node*/
                      end   /*k*/
                   $=word('node='j, 1 +  (j<1) ) /*define a label for this line's output*/
                   say center($, w) substr(_, 2) /*ignore 1st (leading) blank which was */
                   end      /*j*/                /* [↑]         caused by concatenation.*/
          say                                    /*show a blank line to separate outputs*/
          return                                 /* [↑]  extreme indentation to terminal*/