fix errors

cashu/core/base.py

@@ -1047,17 +1047,13 @@ def proofs(self) -> List[Proof]:
         ]
 
     @property
-    def dlc_root(self) -> str:
+    def dlc_root(self) -> Optional[str]:
         return self.r
 
     @property
     def keysets(self) -> List[str]:
         return list(set([p.i.hex() for p in self.t]))
 
-    @property
-    def keysets(self) -> List[str]:
-        return list(set([p.i.hex() for p in self.t]))
-
     @classmethod
     def from_tokenv3(cls, tokenv3: TokenV3):
         if not len(tokenv3.mints) == 1:

cashu/core/crypto/dlc.py

@@ -2,6 +2,8 @@
 from typing import Optional, Tuple
 from secp256k1 import PrivateKey, PublicKey
 
+from typing import List
+
 def sorted_merkle_hash(left: bytes, right: bytes) -> bytes:
     '''Sorts `left` and `right` in non-ascending order and
         computes the hash of their concatenation

cashu/core/nuts.py

@@ -11,3 +11,4 @@
 DETERMINSTIC_SECRETS_NUT = 13
 MPP_NUT = 15
 WEBSOCKETS_NUT = 17
+DLC_NUT = 99