How to make Vim to auto format the name of the function to be capitalize in Go

Question

I use Vim as an editor for coding in Go. I has vim-go installed in my Vim. I wonder if there is a way to auto format the function name to make it capitalize. For example instead of type

fmt.Println("Go is fun")

I would like to just type

fmt.println("Go is fun")

and produce the result of fmt.Println

It would help me type the code smoothly and avoid to let my right little finger to touch to shift button for the method name.