Sign on left vertical bar

Does anyone know which api i can use to put that red m letter on veritical right bar as has shown in image below ?
Whether there is any topic opened already about it sorry but i didn’t find it.

hi_markapi

I’d take a look at how gitsigns or or the lsp plug-ins work (if I were at my computer I’d pull up exactly how this works )

Thanks man

gitsigns uses that nvim_buf_set_extmark()
I might think it can help me.