<!-- Note: for support questions, you are strongly advised to use [Stack Overflow](https://stackoverflow.com/questions/tagged/chisel). -->
<!--
This repository's issues are reserved for feature requests and bug reports.
Please select the item best describing the issue in each category and delete the other items.
-->
<!-- choose all that apply -->
**Type of issue**: bug report | feature request | documentation | other enhancement

<!-- choose one -->
**Impact**: no functional change | API addition (no impact on existing code) | API modification | unknown

<!-- choose one -->
**Development Phase**: request | proposal

**Other information**
 <!-- include detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. Stack Overflow, gitter, etc -->

**If the current behavior is a bug, please provide the steps to reproduce the problem:**

**What is the current behavior?**

**What is the expected behavior?**

**Please tell us about your environment:**
<!--    (examples)
    - version: `3.0-SNAPSHOT`
    - OS: `Linux knight 4.4.0-92-generic #115-Ubuntu SMP Thu Aug 10 09:04:33 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux`
-->
**What is the use case for changing the behavior?**
