config.writeWrites a data field to a config file
|Writes the <key>=<value> pair to the config file identifier by <id>.
<id> must be a valid config file id returned by $config.open().
<key> and <value> can be any strings.
The <key>=<value> pair is written in the current section of the config file.
If <key> already exists in the current section of the config , the corresponding value is replaced with <value>.
If <value> is an empty string, the <key> is simply removed from the current section.
If a section remains empty (with no keys) at file write time, that section will be removed.
The changes are NOT written to disk: you must call config.flush or (better) config.close for the changes to be effectively written.
|config module documentation|