calibration 'evaluator' failed for striped string

I did a side test to verify that a string.strip() failed `asteval`

```
import asteval

def convert(data_i):
  data_i["y"]=1
  return data_i

cal_functions = [convert]

cal_functions = {f.__name__:f for f in cal_functions}
evaluator = asteval.Interpreter(usersyms=cal_functions)
test_1 = evaluator(convert({"x":0}))
print(test_1)
```