[bug] cannot handle nested brace

[Freed-Wu]

  ""
  " foobar
  call g:foobar#utils#plugin.Flag('g:foobar',
        \ get(s:foobar, 0, '')
        \ )

It can work:

                                                     *foobar:g:foobar*
foobar
Default: get(s:foobar, 0, '') `

However, the default of nested brace cannot be detected.

  ""
  " foobar
  call g:foobar#utils#plugin.Flag('g:foobar',
        \ get(split(s:foobar), 0, '')
        \ )

                                                     *foobar:g:foobar*
foobar