andrewberls/regularity — pull request #5 by hughbien (2013-10-12 06:03:27+00:00)
Title: Raise error if appending after #end_with called

Raises an error if a user attempts to append more to the regex after #end_with has already been called:

```
Regularity.new
.start_with(3, :digits)
.end_with('$')
.then('-') # raises Regularity::Error
```

This provides symmetry to the error raised if #start_with gets called and it's not the beginning of the regex.