doc-src/Tutorial/Datatype/tconstssubst

renamings: real_of_nat, real_of_int -> (overloaded) real
inf_close -> approx
SReal -> Reals
SNat -> Nats

consts
   subst  :: ('a => ('a,'b)term) => ('a,'b)term      => ('a,'b)term
   substs :: ('a => ('a,'b)term) => ('a,'b)term list => ('a,'b)term list