code: def provider_of(iface):
      
      def check(value):
          return (
              iface.providedBy(value),
              u"{value!r} does not provide {interface!s}".format(
                  value=value,
                  interface=fullyQualifiedName(iface),
              ),
          )
      return check
docs: Create an invariant requiring the value provides the zope.interface
      ``iface``.