+Dstream &
+Dstream::operator <<(char c)
+{
+ output (to_str (c));
+ return *this;
+}
+
+Dstream&
+Dstream::operator << (Real r)
+{
+ output (to_str (r));
+ return *this;
+}
+Dstream &
+Dstream::operator <<(Rational c)
+{
+ output (c.str ());
+ return *this;
+}
+Dstream &
+Dstream::operator <<(int i)
+{
+ output (to_str(i));
+ return *this;
+}
+