Made a default name for the register (and stored initialized registers)

register.py

@@ -1,8 +1,14 @@
 class Register:
-    def __init__(self, n_bits, name):
+    registers = []
+
+    def __init__(self, n_bits, name=None):
         self.n_bits = n_bits
-        self.name = name
+        if name is None:
+            self.name = "r{}".format(len(Register.registers))
+        else:
+            self.name = name
         self.value = 0
+        Register.registers.append(self)
 
     def truncate(self, value, bits=None):
         if bits is None: