Support LOOKUP on x where x.rank

[zwnop]

Currently lookup by rank is not supported.
It's necessary, hope this feature can be added.
for example :
lookup on rela where rela.rank == 233;

[jievince]

Does rela.rank has index？

[zwnop]

I mean inner prop 'rank' on every edge.
In other word
for example：
lookup on rela where rank(rela) == 233;