diff --git a/dreamer4/dreamer4.py b/dreamer4/dreamer4.py
index d494f77..30029c2 100644
--- a/dreamer4/dreamer4.py
+++ b/dreamer4/dreamer4.py
@@ -74,6 +74,32 @@ def l2norm(t):
 def softclamp(t, value = 50.):
     return (t / value).tanh() * value
 
+# reinforcement learning related
+
+# rewards
+
+class SymExpTwoHot(Module):
+    def __init__(
+        self,
+        range = (-20., 20.),
+        bins = 255
+    ):
+        super().__init__()
+
+        values = torch.linspace(-20., 20., bins)
+        values = values.sign() * (torch.exp(values.abs()) - 1.)
+
+        self.register_buffer('bin_values', values)
+
+    def logits_to_scalar_value(
+        self,
+        logits # (... l)
+    ):
+        raise NotImplementedError
+
+    def forward(self, x):
+        raise NotImplementedError
+
 # golden gate rotary - Jerry Xiong, PhD student at UIUC
 # https://jerryxio.ng/posts/nd-rope/