proposition: Lemma measurable_swap : measurable_fun [set: _] (@swap T1 T2).
proof: Proof. exact: measurable_fun_prod. Qed.
imports: mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality fsbigop ) reals ereal signed topology normedtype sequences esum numfun HB(structures)