LappendIfNotAlready — Check to see if value(s) are already in list, append if not.
New contents of the list.
| ListVarName | Name of the list variable to append to. |
| Values | Value or values to append to the list. |
For information regarding exceptions / errors, see
here.
% set MyList [list one two three]
one two three
% LappendIfNotAlready MyList three
one two three
% LappendIfNotAlready MyList {four five}
one two three four five