Youcompleteme: shortcut key to format selection

Question

According to this documentation

:'<,'>YcmCompleter Format

will format the selected text. I am struggling to map this to shortcut key <S-F2>.

I have tried all of the following after having visually line selected the lines:

Attempt1: vmap <S-F2> :YcmCompleter Format<CR>

Attempt2: nmap <S-F2> :YcmCompleter Format<CR>

Attempt3:

function! YCMFormat()
    silent execute ":'<,'>YcmCompleter Format"
endfunction
vnoremap <S-F2> :call YCMFormat()<CR>

Attempt4:

function! YCMFormat()
    silent execute ":'<,'>YcmCompleter Format"
endfunction
nnoremap <S-F2> :call YCMFormat()<CR>

None of the above work. After hitting these keys, the focus shifts to the bottom command line which displays:

Entering Ex mode.  Type "visual" to go to Normal mode.
:

Is there a way to correctly assign <S-F2> to format the visually selected lines?

Answer 1

As mentioned in the comments, <S-F2> may not work in some terminals or with some vims. Using another key solves the issue of binding it correctly: I would use something like

vnoremap <leader>f :YcmCompleter Format<CR>

But it might also be nice to set formatexpr or indentexpr instead.