making tests deterministic

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/api/python/z3.py

@@ -5787,8 +5787,15 @@ class Solver(Z3PPObject):
         >>> s.assert_and_track(x < 0,  p3)
         >>> print s.check()
         unsat
-        >>> print s.unsat_core()
-        [p3, p1]
+        >>> c = s.unsat_core()
+        >>> len(c)
+        2
+        >>> Bool('p1') in c
+        True
+        >>> Bool('p2') in c
+        False
+        >>> p3 in c
+        True
         """
         if isinstance(p, str):
             p = Bool(p, self.ctx)
@@ -6985,9 +6992,9 @@ def solve(*args, **keywords):
     configure it using the options in `keywords`, adds the constraints
     in `args`, and invokes check.
     
-    >>> a, b = Ints('a b')
-    >>> solve(a + b == 3, Or(a == 0, a == 1), a != 0)
-    [b = 2, a = 1]
+    >>> a = Int('a')
+    >>> solve(a > 0, a < 2)
+    [a = 1]
     """
     s = Solver()
     s.set(**keywords)