[ibus-table] How to disable Lookup Popup

[Thura]

I am writing a simple input system using ibus-table.
My table has a few key sequences like this one.

`a a 1000
`A A 1000

Not really, a and A, but in the same sense as capital letter and lower
letter.
So, I don't want to display a popup (lookup) when ` is pressed, since
it is easy to remember.
Is there any option like NEVER_SHOW_LOOKUP in ibus-table.