Have you ever wished that you could either see what is going on initially at the vim startup like you could do with C program in the gdm mode, but really did not want to go through gdb. Or rather you sometime felt that some function defined by some plugin is causing some issue and you wanted to debug just that function. Well you need not wish anymore, the functionality is already there.
If you want to debut a function then you can simply call the function in debug mode, while you are in vim mode.
You can use continue/next/quit and finish like in any other debugger out there in the wild.
And if you wanted to debug the startup then you can do this :