Implemented simplified CLI interface

flask/helpers.py

@@ -14,7 +14,6 @@ import sys
 import pkgutil
 import posixpath
 import mimetypes
-from datetime import timedelta
 from time import time
 from zlib import adler32
 from threading import RLock
@@ -54,6 +53,13 @@ _os_alt_seps = list(sep for sep in [os.path.sep, os.path.altsep]
                     if sep not in (None, '/'))
 
 
+def get_debug_flag(default=None):
+    val = os.environ.get('FLASK_DEBUG')
+    if not val:
+        return default
+    return val not in ('0', 'false', 'no')
+
+
 def _endpoint_from_view_func(view_func):
     """Internal helper that returns the default endpoint for a given
     function.  This always is the function name.