Implement pack/unpack helpers

pytensor/tensor/__init__.py

@@ -142,6 +142,7 @@ def _get_vector_length_Constant(op: Op | Variable, var: Constant) -> int:
     specify_broadcastable,
     specify_shape,
 )
+from pytensor.tensor.shape_ops import *
 
 # We import as `_shared` instead of `shared` to avoid confusion between
 # `pytensor.shared` and `tensor._shared`.