Update developer_guide_implementing_distribution.md (#4889)

Meenal Jhajharia · web-flow · commit 523d869558a0 · 2021-08-01T09:42:23.000-07:00
diff --git a/docs/source/developer_guide_implementing_distribution.md b/docs/source/developer_guide_implementing_distribution.md
@@ -35,6 +35,7 @@ The following snippet illustrates how to create a new `RandomVariable`:
 
 from aesara.tensor.var import TensorVariable
 from aesara.tensor.random.op import RandomVariable
+from typing import List, Tuple
 
 # Create your own `RandomVariable`...
 class BlahRV(RandomVariable):
