Pass local variables in a vimscript function to python

For example, I want to use default arguments:

function! MakeOrgTable(...)
let l:num_col = a:0 > 0? (a:0) :  0;
python << EOF
import vim
vim.current.buffer[:]=make_table(vim.current.buffer, vim.eval("l:num_col"))
EOF
endfunction

But it doesn't work, Vim cannot find l:num_col. But I do not want define a global variable like g:num_col.

So is there a way to pass local variables in a vimscript function to Python?

I use neovim 0.8.0.