I am done

rl/Lib/site-packages/onnx/reference/ops/op_softplus.py

@@ -0,0 +1,16 @@
+# Copyright (c) ONNX Project Contributors
+
+# SPDX-License-Identifier: Apache-2.0
+from __future__ import annotations
+
+import numpy as np
+
+from onnx.reference.ops._op import OpRunUnaryNum
+
+
+class Softplus(OpRunUnaryNum):
+    def _run(self, X):  # type: ignore
+        tmp = np.exp(X).astype(X.dtype)
+        tmp += 1
+        np.log(tmp, out=tmp)
+        return (tmp,)