CicUniv.universe_graph ->
Cic.substitution * Cic.metasenv * CicUniv.universe_graph
+val unification:
+ Cic.metasenv -> Cic.context -> Cic.term -> Cic.term ->
+ CicUniv.universe_graph ->
+ Cic.substitution * Cic.metasenv * CicUniv.universe_graph
+
(**
Performs the beta expansion of the term "where" w.r.t. "what",
i.e. returns the list of all the terms t s.t. "(t what) = where".