Test that mutual recursion works for Ometa V1 syntax

Working on issue 57

ometa/test/test_pymeta.py

@@ -359,6 +359,23 @@ def test_leftrecursion(self):
          self.assertEqual(g.num("32767"), 32767)
 
 
+    def test_mutual_leftrecursion(self):
+         g = self.compile("""
+               num ::= (<num>:n <digit>:d   => n * 10 + d
+                      | <digit>)
+               digit ::= :x ?(x.isdigit()) => int(x)
+               x ::= <expr>
+               expr ::= <expr>:e '-' <num>:n => e - n
+                       | <num>
+              """)
+         self.assertEqual(g.expr("3"), 3)
+         self.assertEqual(g.expr("3-2"), 1)
+         self.assertEqual(g.expr("3-2-1"), 0)
+         self.assertEqual(g.x("3"), 3)
+         self.assertEqual(g.x("3-2"), 1)
+         self.assertEqual(g.x("3-2-1"), 0)
+
+
     def test_characterVsSequence(self):
         """
         Characters (in single-quotes) are not regarded as sequences.