Parameter preserve_order is not work

[hauturier]

I tested preserve_order with following code snippet:

>>> import rjsonnet
>>> rjsonnet.evaluate_snippet("", "{'b': 100.0 + 0.0, 'a':2}", preserve_order=True)

But the result doesn't keep the order with inputs:

'{\n    "a": 2,\n    "b": 100\n}'

And when I test this by running command from jrsonnet:

jrsonnet --exp-preserve-order -e '{'b': 100.0 + 0.0, 'a':2}'

The result keeps the order with inputs:

{
   "b": 100,
   "a": 2
}