python3-zope.interface 4.1.3-1build1 (amd64 binary) in ubuntu xenial

 This package provides an implementation of object interfaces for Python.
 Interfaces are a mechanism for labeling objects as conforming to a given API
 or contract. So, this package can be considered as implementation of the
 Design By Contract methodology support in Python.
 .
 This is the Python 3 version.