public override System.String ToString()
{
System.Text.StringBuilder s = new System.Text.StringBuilder();
int _arity = arity();
s.Append("[");
for (int i = 0; i < _arity; i++)
{
if (i > 0)
s.Append(",");
s.Append(elems[i].ToString());
}
s.Append("]");
return s.ToString();
}