change mu to mean in ZIP

Author: theorashid

pymc/distributions/discrete.py

@@ -1323,10 +1323,10 @@ def dist(cls, psi, theta, *args, **kwargs):
         return super().dist([psi, theta], *args, **kwargs)
 
     def get_moment(rv, size, psi, theta):
-        mu = at.floor(psi * theta)
+        mean = at.floor(psi * theta)
         if not rv_size_is_none(size):
-            mu = at.full(size, mu)
-        return mu
+            mean = at.full(size, mean)
+        return mean
 
     def logp(value, psi, theta):
         r"""