add some generic datatypes

aman/types/Exception.py

@@ -0,0 +1,13 @@
+#!/usr/bin/env python
+
+class Error(Exception):
+    pass
+
+class FormatError(Error):
+    def __init__(self, message):
+        self.message = message
+
+class InputError(Error):
+    def __init__(self, expression, message):
+        self.expression = expression
+        self.message = message