keep ital and bold on paste

[pat123456]

Hello,

I would like, when an user copie some text from internet page, word... or anywhere else and paste it in the contenteditable div, that the italic and bold element will not be removed.

Is there an option in medium.js to do that ?
Else is there a part of the code that I can change to do that, without breaking the all code ?

Sorry my bad english