editable plugin. how to use .valid()?

fbas

when setting a cssclass to a column, the editable plugin (line 185) calls .valid(). In my case, valid() was not defined, crashing my app.
[code]
if (!input.valid() || 0 == input.valid())
return false;
else
return true;
[/code]

for now I've added a test to see if valid() is defined, but since I don't know what it does or how to use it properly, I want to make sure I'm not disabling something worthwhile.
[code
if ((input.valid) && (!input.valid() || 0 == input.valid()) )
return false;
else
return true;
[/code]

if this is related to jquery.validate(), it's probably not relevant to my needs. http://docs.jquery.com/Plugins/Validation/valid