add pt2tf tool

pt2tf/onnx-tensorflow/onnx_tf/handlers/backend/math_mixin.py

@@ -0,0 +1,25 @@
+import copy
+
+from .broadcast_mixin import BroadcastMixin
+
+
+class BasicMathMixin(BroadcastMixin):
+  pass
+
+
+class ArithmeticMixin(BroadcastMixin):
+  pass
+
+
+class ReductionMixin(BroadcastMixin):
+
+  @classmethod
+  def _common(cls, node, **kwargs):
+    attrs = copy.deepcopy(node.attrs)
+    axis = attrs.pop("axes", None)
+    if isinstance(axis, (list, tuple)) and len(axis) == 1:
+      axis = axis[0]
+    attrs["axis"] = axis
+    # https://github.com/onnx/onnx/issues/585
+    attrs["keepdims"] = attrs.pop("keepdims", 1) == 1
+    return [cls.make_tensor_from_onnx_node(node, attrs=attrs, **kwargs)]