Private method to return the fraction of results available, as a real number
        between 0 and 1. This does not update the results fetched from the cluster.

        :returns: the fraction of available results

def _availableResultsFraction( self ):
        """Private method to return the fraction of results available, as a real number
        between 0 and 1. This does not update the results fetched from the cluster.

        :returns: the fraction of available results"""
        tr = self.notebook().numberOfResults() + self.notebook().numberOfPendingResults()
        if tr == 0:
            return 0
        else:
            return (self.notebook().numberOfResults() + 0.0) / tr