Module EnvSA.
Existing Instance Join_env.
Existing Instance Perm_env.
Existing Instance Sep_env.
Existing Instance Sing_env.
Existing Instance Canc_env.
Existing Instance Disj_env.
Existing Instance Cross_env.

Lemma empty_env_unit {key: Type}{A: Type}:
forall rho: env key A, unit_for empty_env rho.