Fitting function for vistrails wrapper

Three fitting functions are created for vt wrapper.

gaussian
lorentzian
lorentzian squared
Is there a way to parametrize these functions?  They look very similar to me.  I think something like:

```python
def _three_param_fit_fatory(model):
    def inner(input_data , area, area_vary, area_range, 
                    center, center_vary, center_range,
                     sigma, sigma_vary, sigma_range):
        return some_body_code()
    inner.__doc__ = doc_template.format(model.name)
    inner.__name__ = name_template(model.name.lower())
    return inner

mod = sys.modules[__name__]
for m in ModelList:
    func = _three_param_fit_factory(m)
    setattr(mod, func.__name__, func)
```

will work.