convert arguments in get_moment

Author: farhanreynaldo

pymc/distributions/discrete.py

@@ -926,8 +926,9 @@ def dist(cls, N, k, n, *args, **kwargs):
         n = at.as_tensor_variable(intX(n))
         return super().dist([good, bad, n], *args, **kwargs)
 
-    def get_moment(rv, size, N, k, n):
-        mode = intX(at.floor((n + 1) * (k + 1) / (N + 2)))
+    def get_moment(rv, size, good, bad, n):
+        N, k = good + bad, good
+        mode = at.floor((n + 1) * (k + 1) / (N + 2))
         if not rv_size_is_none(size):
             mode = at.full(size, mode)
         return mode