Some chain methods converted to classmethod

Author: carver

eth/chains/base.py

@@ -149,11 +149,12 @@ def from_genesis_header(cls,
     #
     # VM API
     #
-    def get_vm_class(self, header: BlockHeader) -> Type['BaseVM']:
+    @classmethod
+    def get_vm_class(cls, header: BlockHeader) -> Type['BaseVM']:
         """
         Returns the VM instance for the given block number.
         """
-        return self.get_vm_class_for_block_number(header.block_number)
+        return cls.get_vm_class_for_block_number(header.block_number)
 
     @abstractmethod
     def get_vm(self, header: BlockHeader=None) -> 'BaseVM':

eth/vm/base.py

@@ -238,8 +238,9 @@ def get_uncle_reward(block_number: int, uncle: BaseBlock) -> int:
     def create_transaction(self, *args, **kwargs):
         raise NotImplementedError("VM classes must implement this method")
 
+    @classmethod
     @abstractmethod
-    def create_unsigned_transaction(self, *args, **kwargs):
+    def create_unsigned_transaction(cls, *args, **kwargs):
         raise NotImplementedError("VM classes must implement this method")
 
     @classmethod
@@ -646,11 +647,12 @@ def create_transaction(self, *args, **kwargs):
         """
         return self.get_transaction_class()(*args, **kwargs)
 
-    def create_unsigned_transaction(self, *args, **kwargs):
+    @classmethod
+    def create_unsigned_transaction(cls, *args, **kwargs):
         """
         Proxy for instantiating an unsigned transaction for this VM.
         """
-        return self.get_transaction_class().create_unsigned_transaction(*args, **kwargs)
+        return cls.get_transaction_class().create_unsigned_transaction(*args, **kwargs)
 
     @classmethod
     def get_transaction_class(cls):