vim的py中字典与赋值间转换

'foo' : 'bar',      
//<=>
  foo = 'bar'

但想用.多次运行.

function! s:var2dict(...)
  if a:0
    "动作"
    " let save_cursor = getcurpos()"
    execute "normal! I'\<ESC>ea'\<ESC>f=r:A,\<ESC>j^"
    " call setpos('.', save_cursor)"
    " unlet save_cursor"
  else
    "安装"
    let &operatorfunc = matchstr(expand('<sfile>'), '[^. ]*$')
    echom &operatorfunc
    return "g@\<space>"
  endif
endfunction
nnoremap <expr> <leader>{ <sid>var2dict()

:h operatorfunc,此映射为,按下.时执行的操作