local curline = vim.api.nvim_buf_get_lines(0, linenr - 1, linenr, false)[1]
        print(string.format('Line [%d] has %d bytes', linenr, #curline))
        EOF
        endfunction
<
    Note that the `local` variables will disappear when the block finishes.
    But not globals.

                                                                      *:luado*
:[range]luado {body}
    Executes Lua chunk "function(line, linenr) {body} end" for each buffer
    line in [range], where `line` is the current line text (without <EOL>),
    and `linenr` is the current line number. If the function returns a string
    that becomes the text of the corresponding buffer line. Default [range] is
    the whole file: "1,$".

    Examples: >vim
        :luado return string.format("%s\t%d", line:reverse(), #line)

        :lua require"lpeg"
        :lua -- balanced parenthesis grammar:
        :lua bp = lpeg.P{ "(" * ((1 - lpeg.S"()") + lpeg.V(1))^0 * ")" }
        :luado if bp:match(line) then return "=>\t" .. line end
<
                                                                    *:luafile*
:luafile {file}
    Execute Lua script in {file}.
    The whole argument is used as the filename (like |:edit|), spaces do not
    need to be escaped. Alternatively you can |:source| Lua files.

    Examples: >vim
        :luafile script.lua
        :luafile %
<

==============================================================================
luaeval()                                                 *lua-eval*

The (dual) equivalent of "vim.eval" for passing Lua values to Nvim is
"luaeval". "luaeval" takes an expression string and an optional argument used
for _A inside expression and returns the result of the expression. It is
semantically equivalent in Lua to: >lua

    local chunkheader = "local _A = select(1, ...) return "
    function luaeval (expstr, arg)
        local chunk = assert(loadstring(chunkheader .. expstr, "luaeval"))
        return chunk(arg) -- return typval
    end
<
Lua nils, numbers, strings, tables and booleans are converted to their
respective Vimscript types. If a Lua string contains a NUL byte, it will be
converted to a |Blob|. Conversion of other Lua types is an error.

The magic global "_A" contains the second argument to luaeval().

Example: >vim
    :echo luaeval('_A[1] + _A[2]', [40, 2])
    " 42
    :echo luaeval('string.match(_A, "[a-z]+")', 'XYXfoo123')
    " foo
<
                                                         *lua-table-ambiguous*
Lua tables are used as both dictionaries and lists, so it is impossible to
decide whether empty table is a list or a dict. Also Lua does not have integer
numbers. To disambiguate these cases, we define:
                                                                    *lua-list*
0. Empty table is a list. Use |vim.empty_dict()| to represent empty dict.
1. Table with N consecutive (no `nil` values, aka "holes") integer keys 1…N is
   a list. See also |list-iterator|.
                                                                    *lua-dict*
2. Table with string keys, none of which contains NUL byte, is a dict.
3. Table with string keys, at least one of which contains NUL byte, is also
   considered to be a dictionary, but this time it is converted to
   a |msgpack-special-map|.
                                                             *lua-special-tbl*
4. Table with `vim.type_idx` key may be a dictionary, a list or floating-point
   value:
   - `{[vim.type_idx]=vim.types.float, [vim.val_idx]=1}` is converted to
     a floating-point 1.0. Note that by default integral Lua numbers are
     converted to |Number|s, non-integral are converted to |Float|s. This
     variant allows integral |Float|s.
   - `{[vim.type_idx]=vim.types.dictionary}` is converted to an empty
     dictionary, `{[vim.type_idx]=vim.types.dictionary, [42]=1, a=2}` is
     converted to a dictionary `{'a': 42}`: non-string keys are ignored.
     Without `vim.type_idx` key tables with keys not fitting in 1., 2.