Rename Config.value_format to value_formatter

pygal/config.py

@@ -154,7 +154,7 @@ class Config(object):
         False, bool, "Value", "Display values in human readable format",
         "(ie: 12.4M)")
 
-    value_format = Key(
+    value_formatter = Key(
         None, type(lambda: 1), "Value",
         "A function to convert numeric value to strings")
 

pygal/graph/base.py

@@ -80,7 +80,8 @@ class BaseGraph(object):
     @property
     def _format(self):
         """Return the value formatter for this graph"""
-        return self.value_format or (humanize if self.human_readable else str)
+        return self.value_formatter or (
+            humanize if self.human_readable else str)
 
     def _compute(self):
         """Initial computations to draw the graph"""