Removed unused imports and bump version to v4.2.2

Merge pull request #240 from aagarwal1012/v4.2.0

Bump version to `v4.2.0`

Merge pull request #181 from awhitford/release310

Prep release for Version 3.1.0

Merge pull request #177 from awhitford/release302

Prep for release 3.0.2

Tweaked an assertion validating repeat properties.

bump version to v2.5.4

Merge pull request #146 from awhitford/release253

Patch Release 2.5.3.

bump version to v2.5.0

bump version to v2.4.0

bump version to v2.3.0