(self, a,b)
| 46 | def all_rewritings(self,var): |
| 47 | pass |
| 48 | def rewrite(self, a,b): |
| 49 | a=self.canonical(a) |
| 50 | b=self.canonical(b) |
| 51 | if not a==b: |
| 52 | self.mydict[a]=b |
| 53 | def __getitem__(self,key): |
| 54 | return self.canonical(key) |
| 55 | def __setitem__(self, val, key): |