Test if object is an equivalence_pair
Examples
exp_spec <- model_spec(
loglik_fn = function(y, lambda) sum(dexp(y, rate = lambda, log = TRUE)),
par_names = "lambda"
)
pair <- equivalence_pair(exp_spec, exp_spec)
is_equivalence_pair(pair) # TRUE
is_equivalence_pair(list())
is_equivalence_pair(list()) # FALSE