require("nvterm").setup()

local terminal = require("nvterm.terminal")

local ft_cmds = {
  python = "python3 " .. vim.fn.expand('%'),
  ...
  --<your commands here>
}
local toggle_modes = { 'n', 't' }
local mappings = {
  { 'n',          '<C-l>', function() terminal.send(ft_cmds[vim.bo.filetype]) end },
  { toggle_modes, '<A-h>', function() terminal.toggle('horizontal') end },
  { toggle_modes, '<A-v>', function() terminal.toggle('vertical') end },
  { toggle_modes, '<A-i>', function() terminal.toggle('float') end },
}
local opts = { noremap = true, silent = true }
for _, mapping in ipairs(mappings) do
  vim.keymap.set(mapping[1], mapping[2], mapping[3], opts)
end