Epicenter Release Notes: v1.38.1 | Documentation

v1.38.1 Release Notes

Release Date: 5/20/2016

SimLang operation to step back. There is a new SimLang operation, goBack(). When called, the operation causes your SimLang model to go backwards one time unit. After the goBack() operation is complete, the sim is at the end of the previous step, with the decisions for that (previous) step still present.
- For example, consider the following sequence of calls:
```
  step()   // advance from step 1 to step 2
  step()   // advance from step 2 to step 3
  step(2)  // advance from step 3 to step 5
  goBack() // go back from step 5 to step 4, with decisions made in step 4
```
- As with other SimLang operations, you can call this operation from your simulation in several ways:
  - If you are using the UI Builder, some components (like buttons) include a Model Operation property that you can specify. When the end user interacts with the component (e.g. by clicking the button), the operation is called.
  - If you are writing your own user interface code, you can call the operation through Flow.js, Epicenter.js, or the Run API.
- See more information.

In rare cases, if a model session timed out immediately before a model operation was called, the operation was called anyway and returned with a 404 error. This has been corrected; the run is now properly restored from the Epicenter backend database to memory before the operation is called. See additional background on run persistence.