emolch/pyrocko — pull request #25 by HerrMuellerluedenscheid (2014-04-06 14:45:43+00:00)
Title: PoleZeroResponse: poles and zeros default-> empty list

If zeros or poles was an empty list it woudn't be listed in the concerning yaml dump at all, causing guts.load_string() to raise an exception. The default=[()] solves this.