recipe engine: remove Path.default_tostring_fn

recipe_engine/config_types.py

Index: recipe_engine/config_types.py
diff --git a/recipe_engine/config_types.py b/recipe_engine/config_types.py
index bcfefe567cb58c5e7b67db055e45ba95df0eb32e..54f7b378883646f5a5477c359bd0d4697662b569 100644
--- a/recipe_engine/config_types.py
+++ b/recipe_engine/config_types.py
@@ -59,7 +59,7 @@ class RecipeConfigType(object):
     cls._TOSTRING_MAP[cls.__name__] = new_tostring_fn
 
   def default_tostring_fn(self):
-    raise NotImplementedError
+    raise NotImplementedError()
 
   def __str__(self):
     return self.tostring_fn(self) # pylint: disable=not-callable
@@ -160,15 +160,6 @@ class Path(RecipeConfigType):
       return False
     return child.pieces[:len(self.pieces)] == self.pieces
 
-  def default_tostring_fn(self):
-    suffix = ''
-    if self.platform_ext:
-      suffix = ', platform_ext=%r' % (self.platform_ext,)
-    pieces = ''
-    if self.pieces:
-      pieces = ', ' + (', '.join(map(repr, self.pieces)))
-    return 'Path(\'%s\'%s%s)' % (self.base, pieces, suffix)
-
   def __repr__(self):
     s = "Path(%r" % self.base
     if self.pieces: