Add type hints

Author: canyon289

pymc/distributions/timeseries.py

@@ -281,7 +281,7 @@ def dist(
     #     return moment
 
     def logp(
-        value,
+        value: Union[at.TensorVariable, at.TensorConstant],
         mu: Union[at.TensorVariable, at.TensorConstant],
         sigma: Union[at.TensorVariable, at.TensorConstant],
         init: Union[at.TensorVariable, at.TensorConstant],