Given vim:
  function! s:func(a, b)
  endfunc
  let s:var = 'foo'
  execute 'let s:var = "bar"'
  echomsg s:var
  let s:var = 'foo'
  function! s:func(a, b)
  endfunc
  let foo = function('s:func')
  let foo = function("s:func")

Execute (:call lookup#lookup() cycles through script-local variables):
  normal! 3GwE
  AssertEqual [3, 9], [line('.'), col('.')]
  call lookup#lookup()
  AssertEqual [3, 7], [line('.'), col('.')]
  call lookup#lookup()
  AssertEqual [6, 7], [line('.'), col('.')]
  call lookup#lookup()
  AssertEqual [4, 16], [line('.'), col('.')]
  call lookup#lookup()
  AssertEqual [3, 7], [line('.'), col('.')]

Execute (:call lookup#lookup() cycles through script-local functions):
  normal! 9G7w
  AssertEqual [9, 23], [line('.'), col('.')]
  call lookup#lookup()
  AssertEqual [7, 13], [line('.'), col('.')]
  call lookup#pop()
  normal! j
  AssertEqual [10, 23], [line('.'), col('.')]
  call lookup#lookup()
  AssertEqual [7, 13], [line('.'), col('.')]
  call lookup#lookup()
  AssertEqual [1, 13], [line('.'), col('.')]
  call lookup#lookup()
  AssertEqual [7, 13], [line('.'), col('.')]