chore: import upstream snapshot with attribution

python/dgl/function/base.py

@@ -0,0 +1,31 @@
+"""Built-in function base class"""
+from __future__ import absolute_import
+
+__all__ = ["BuiltinFunction", "TargetCode"]
+
+
+class TargetCode(object):
+    """Code for target
+
+    Note: must be consistent with the target code definition in C++ side:
+          src/kernel/binary_reduce_common.h
+    """
+
+    SRC = 0
+    DST = 1
+    EDGE = 2
+
+    CODE2STR = {
+        0: "u",
+        1: "v",
+        2: "e",
+    }
+
+
+class BuiltinFunction(object):
+    """Base builtin function class."""
+
+    @property
+    def name(self):
+        """Return the name of this builtin function."""
+        raise NotImplementedError