sil update
let [s:lhs,s:rhs] = [{'|':'bar'}, {'|':'bar', "'":"''"}]
for ord in range(33,61)+range(63,90)+range(92,126)
  let char = nr2char(ord)
  let [l,r] = [get(s:lhs, char, char), get(s:rhs, char, char)]
  exe printf("nnore <m-%s> :echo 'M-%s PRESSED'<cr>", l, r)
  exe printf("nnore <f20><m-%s> :let g:lastmap = '%s'<cr>", l, r)
endfor
for ord in range(33,61)+range(63,90)+range(92,126)
  let char = nr2char(ord)
  sil call feedkeys("\<f20>\<esc>".char, 'Tx')
  if get(g:, 'lastmap') != get(s:lhs, char, char)
    echom 'Broken' '<m-'.char.'>'
  endif
endfor
if &mod | sil earlier 1f | endif

" to test:
"   1. paste this file into, for example, /tmp/meta_test.vim and open /tmp/meta_test.vim in vim
"   2. :source %   " to source the file and run tests
"   3. :messages   " to show the errors from the tests
"   4. press Meta a or any other meta sequence to test
"      - it will print "M-a" (or whatever) to the cmdline