Get an environment representing the context directly before executing a given stage.
stageRunner_.before_env(stage_index)
| stage_index | integer. The substage for which to grab the before environment. |
|---|
a fresh new environment representing what would have been in the context as of right before the execution of that substage.
If there is a lot of data in the remembered environment, this function may be computationally expensive as it has to create a new environment with a copy of all the relevant data.