const
max = 50; { max. number of nodes - user may modify}
type
treelement = integer;{user may modify}
treenode = record
left,
right: integer;
element: treelement;
end;
treeforest = record
a: integer; { "available" chain }
space: array[1..max] of treenode;
end;
tree = integer;
procedure visit(var out:text; e:treelement);
{+--- on entry tree has been defined, element e exists
| on exit treelement e is printed legibly to 'out'
+---------------------------------------------------------}