Numeric formatting of negative number using () in datatable field

I use the format:webix.i18n.priceFormat to display a price currency number.
For negative number I get for example: $-48.40
I would like to have negative numbers in the format : ($48.40)
How to get this format in webix ? Probably i have to define a custom template.
Of course i can format the data as a string during the load from server (by ajax php) but in this way I loss the “numeric” type of the field (I cannot make operations on it)
Any solution ?
Thanks