neovim_tab_chicanery.lua

  -- vim.g.last_tab_page_handler = nil
  -- LastTabPageHandler = nil

  function TabSwitch(handler)
    local curr_handler = vim.api.nvim_get_current_tabpage()
    local next_handler = handler

    -- if (handler == curr_handler) then
    --   next_handler = LastTabPageHandler
    --   LastTabPageHandler = curr_handler
    -- end

    if (next_handler ~= nil) then
      vim.api.nvim_set_current_tabpage(next_handler)
    end
  end

  function TabCreate(n)
    vim.cmd [[tabnew]]
  end

  function TabChicanery(n)
    local tab_page_handlers = vim.api.nvim_list_tabpages()

    if (n > #tab_page_handlers) then
      if (n == #tab_page_handlers+1) then
        TabCreate(n)
      end
    else
      TabSwitch(tab_page_handlers[n])
    end
  end

  for n = 1, 9 do
    vim.keymap.set('n', '<A-'..n..'>',      function() TabChicanery(n) end)
  end
  
  vim.keymap.set('n', '<A-l>',       '<CMD>tabnext<CR>')
  vim.keymap.set('n', '<A-h>',       '<CMD>tabprevious<CR>')