public override Expr VisitNAryExpr(NAryExpr node)
        {
            var funCall = node.Fun as FunctionCall;

            if (funCall != null)
            {
                if (currentDeclaration != null)
                {
                    currentDeclaration.AddFunctionDependency(funCall.Func);
                }
                if (currentAxiom != null)
                {
                    currentAxiom.AddFunctionDependency(funCall.Func);
                }
            }

            return(base.VisitNAryExpr(node));
        }