docs: def parse_uri(uri):
          ''' parse URI
          '''
          if not uri or uri.find('://') <= 0:
              raise RuntimeError('Incorrect URI definition: {}'.format(uri))
          backend, rest_uri = uri.split('://')
          if backend not in SUPPORTED_BACKENDS:
              raise RuntimeError('Unknown backend: {}'.format(backend))
          database, table = rest_uri.rsplit(':',1)
  
          return database, table