- set trie($this,to,$ch) $to
- set trie($this,combining,$ch) $combining
- set trie($this,codename,$ch) $codename
+ if {![info exist trie($this,to,$ch)]} {
+ set trie($this,to,$ch) $to
+ set trie($this,combining,$ch) $combining
+ set trie($this,codename,$ch) $codename
+ }