Does not work with ATP plugin

With the Automatic Latex plugin for vim, any command leads to this error:

``` python
Error detected while processing function 18_VCalc_REPL:
line 11:
Traceback (most recent call last):
File "", line 1, in
File "", line 6, in repl
File "/home/user/.vim/plugin/vimcalc.py", line 258, in parse
lineNode = line(tokens)
TypeError: 'str' object is not callable
```