Writing own api in go language to access id of user through email or username

I need a new api in mattermost. Since I am not familiar in go language, I need a help to write a simple api in the mattermost current v3 version. I have created an issue for the problem I have face here in github as well. Please help me to figure out this problem.

Hi @rosunshrestha,

Can you submit a feature request for this?