code: def _find(self, url):
          
          # Query the permanent view to find a url
          vr = self.db.view("properties/by_url", key=url, include_docs=True)
          _logger.debug("find(%r) returned %s" % (url, len(vr)))
          assert len(vr) <= 1, "Found multiple matches for %r" % url
          for row in vr:
              assert row.doc
              return row.doc
          return None
docs: Return properties document for path.