Start adding normalizers instead of the get_code(normalize=True) function.

parso/normalizer.py

@@ -0,0 +1,13 @@
+class Normalizer():
+    def normalize(self, leaf):
+        return leaf.prefix + leaf.value
+
+    def iter_errors(self, leaf):
+        return iter([])
+
+
+class Error():
+    def __init__(self, leaf, code, message):
+        self._leaf = leaf
+        self.code = code
+        self.message = message