3. The method of claim 1 , wherein step (d) comprises using heuristic rules to group the set of deep tokens appearing in the set of current tokens.
3. The method of claim 1 , wherein step (d) comprises using heuristic rules to group the set of deep tokens appearing in the set of current tokens. 9. The method of claim 3 , wherein using the heuristic rules comprises considering a position, within a token of the set of current tokens, of a deep token selected as an anchor.