private Expr MakeBVFunctionCall(string functionName, string smtName, Type resultType, params Expr[] args)
{
Function f = verifier.GetOrCreateBVFunction(functionName, smtName, resultType, args.Select(a => a.Type).ToArray());
var e = new NAryExpr(Token.NoToken, new FunctionCall(f), new List <Expr>(args));
e.Type = resultType;
return(e);
}