Wrong intent when calling to_lua_source()

[penguinol]

for example, a lua file like:

local a = 0
if a == 0 then
    if a == 1 then
        if a == 2 then
            if a == 3 then

            end
        end
    end
end

I loaded the lua source by ast, and then rewrite the ast to source.

lua_ast = ast.parse(content)
tree = ast.parse(content)
print(ast.to_lua_source(tree))

the output is like

local a = 0
if a == 0 then
  if a == 1 then
      if a == 2 then
            if a == 3 then

            else

            end
      else

      end
  else

  end
else

end