Try to add syntax errors to pep8 normalizing.

parso/normalizer.py

@@ -7,6 +7,7 @@ class Normalizer(object):
         self.issues = []
 
     def walk(self, node):
+        self.initialize(node)
         value = self.visit(node)
         self.finalize()
         return value
@@ -27,6 +28,9 @@ class Normalizer(object):
     def visit_leaf(self, leaf):
         return leaf.prefix + leaf.value
 
+    def initialize(self, node):
+        pass
+
     def finalize(self):
         pass