Add open issues. (Needs more work.)

pep-0239.txt

@@ -57,6 +57,21 @@ The rational() Builtin
         rational(n, d) * d == n
 
 
+Open Issues
+
+    - Maybe the type should be called rat instead of rational.
+      Somebody proposed that we have "abstract" pure mathematical
+      types named complex, real, rational, integer, and "concrete"
+      representation types with names like float, rat, long, int.
+
+    - Should a rational number with an integer value be allowed as a
+      sequence index?  For example, should s[5/3 - 2/3] be equivalent
+      to s[1]?
+
+    - Should shift and mask operators be allowed for rational numbers?
+      For rational numbers with integer values?
+
+
 References
 
     [1] PEP 240, Adding a Rational Literal to Python, Zadka,