state_vars_test3.m:011: Error: no clauses for function `f'/1.
state_vars_test3.m:017: Error: clause for function `f'/2
state_vars_test3.m:017:   without corresponding `:- func' declaration.
state_vars_test3.m:017:   However, a function of that name does exist with
state_vars_test3.m:017:   arity 1.
state_vars_test3.m:017: Error: !Y cannot be a function result.
state_vars_test3.m:017:   You probably meant !:Y.