end
-- Everything that exists before we start loading the live files is frozen and
-- can't be edited live.
function app.freeze_all_existing_definitions()
  app.Frozen_definitions = {on=true}  -- special case for version 1
  local done = {}
  done[app.Frozen_definitions]=true
  app.freeze_all_existing_definitions_in(_G, {}, done)
end
function app.freeze_all_existing_definitions_in(tab, scopes, done)
  -- track duplicates to avoid cycles like _G._G, _G._G._G, etc.
  if done[tab] then return end
  done[tab] = true
  for name,binding in pairs(tab) do
    local full_name = app.full_name(scopes, name)
--?     print(full_name)
    app.Frozen_definitions[full_name] = true
    if type(binding) == 'table' and full_name ~= 'package' then  -- var 'package' contains copies of all modules, but not the best name; rely on people to not modify package.loaded.io.open, etc.
      table.insert(scopes, name)
      app.freeze_all_existing_definitions_in(binding, scopes, done)
      table.remove(scopes)
    end
  end
end
function app.full_name(scopes, name)
  local ns = table.concat(scopes, '.')
  if #ns == 0 then return name end
  return ns..'.'..name

end
-- Everything that exists before we start loading the live files is frozen and
-- can't be edited live.
function app.freeze_all_existing_definitions()
  app.Frozen_definitions = {on=true}  -- special case for version 1
  local done = {}
  done[app.Frozen_definitions]=true
  app.freeze_all_existing_definitions_in(_G, {}, done)

function app.freeze_all_existing_definitions_in(tab, scopes, done)
  -- track duplicates to avoid cycles like _G._G, _G._G._G, etc.
  if done[tab] then return end
  done[tab] = true
  for name,binding in pairs(tab) do
    local full_name = app.full_name(scopes, name)
--?     print(full_name)
    app.Frozen_definitions[full_name] = true
    if type(binding) == 'table' and full_name ~= 'package' then  -- var 'package' contains copies of all modules, but not the best name; rely on people to not modify package.loaded.io.open, etc.
      table.insert(scopes, name)
      app.freeze_all_existing_definitions_in(binding, scopes, done)
      table.remove(scopes)
    end
  end
end
function app.full_name(scopes, name)
  local ns = table.concat(scopes, '.')
  if #ns == 0 then return name end
  return ns..'.'..name
end