Tensorflow 2.x backend: multiple outputs extension of DeepONet (#1533)

Author: vl-dud

deepxde/nn/tensorflow/__init__.py

@@ -1,6 +1,13 @@
 """Package for tensorflow NN modules."""
 
-__all__ = ["DeepONet", "DeepONetCartesianProd", "FNN", "NN", "PFNN", "PODDeepONet"]
+__all__ = [
+    "DeepONet",
+    "DeepONetCartesianProd",
+    "FNN",
+    "NN",
+    "PFNN",
+    "PODDeepONet",
+]
 
 from .deeponet import DeepONet, DeepONetCartesianProd, PODDeepONet
 from .fnn import FNN, PFNN