Get a list of tags and the number of each.

        Returns
        -------
        List of tuples, in order (tag, # of Symbols w/Tag)

def tag_counts(self):
        """ Get a list of tags and the number of each.

        Returns
        -------
        List of tuples, in order (tag, # of Symbols w/Tag)
        
        """                    
        qry = self.ses.query(SymbolTag.tag, func.count(SymbolTag.tag))
        qry = qry.group_by(SymbolTag.tag)
        qry = qry.order_by(SymbolTag.tag)
        tags = list(qry.all())
        return tags