Returns the term object for the supplied identifier
        @type term_id: string
        @param term_id: term identifier

def get_term(self,term_id):
        """
        Returns the term object for the supplied identifier
        @type term_id: string
        @param term_id: term identifier
        """
        if term_id in self.idx:
            return Cterm(self.idx[term_id],self.type)
        else:
            return None