prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  support@gittip.com still linked several places
  Should be support@gratipay.com, right? ;-)
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `gratipay/exceptions.py`
  Content:
  ```
  1 """
  2 This module contains exceptions shared across application code.
  3 """
  4 
  5 from __future__ import print_function, unicode_literals
  6 
  7 
  8 class ProblemChangingUsername(Exception):
  9     def __str__(self):
  10         return self.msg.format(self.args[0])
  11 
  12 class UsernameIsEmpty(ProblemChangingUsername):
  13     msg = "You need to provide a username!"
  14 
  15 class UsernameTooLong(ProblemChangingUsername):
  16     msg = "The username '{}' is too long."
  17 
  18 class UsernameContainsInvalidCharacters(ProblemChangingUsername):
  19     msg = "The username '{}' contains invalid characters."
  20 
  21 class UsernameIsRestricted(ProblemChangingUsername):
  22     msg = "The username '{}' is restricted."
  23 
  24 class UsernameAlreadyTaken(ProblemChangingUsername):
  25     msg = "The username '{}' is already taken."
  26 
  27 
  28 class ProblemChangingNumber(Exception):
  29     def __str__(self):
  30         return self.msg
  31 
  32 class HasBigTips(ProblemChangingNumber):
  33     msg = "You receive tips too large for an individual. Please contact support@gittip.com."
  34 
  35 
  36 class TooGreedy(Exception): pass
  37 class NoSelfTipping(Exception): pass
  38 class NoTippee(Exception): pass
  39 class BadAmount(Exception): pass
  40 class UserDoesntAcceptTips(Exception): pass
  41 
  42 class FailedToReserveUsername(Exception): pass
  43 
  44 class NegativeBalance(Exception):
  45     def __str__(self):
  46         return "Negative balance not allowed in this context."
  47 
  48 class NotWhitelisted(Exception): pass
  49 class NoBalancedCustomerHref(Exception): pass
  50
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/gratipay/exceptions.py b/gratipay/exceptions.py
  --- a/gratipay/exceptions.py
  +++ b/gratipay/exceptions.py
  @@ -30,7 +30,7 @@
           return self.msg
   
   class HasBigTips(ProblemChangingNumber):
  -    msg = "You receive tips too large for an individual. Please contact support@gittip.com."
  +    msg = "You receive tips too large for an individual. Please contact support@gratipay.com."
   
   
   class TooGreedy(Exception): pass
  
verification_info: {"golden_diff": "diff --git a/gratipay/exceptions.py b/gratipay/exceptions.py\n--- a/gratipay/exceptions.py\n+++ b/gratipay/exceptions.py\n@@ -30,7 +30,7 @@\n         return self.msg\n \n class HasBigTips(ProblemChangingNumber):\n-    msg = \"You receive tips too large for an individual. Please contact support@gittip.com.\"\n+    msg = \"You receive tips too large for an individual. Please contact support@gratipay.com.\"\n \n \n class TooGreedy(Exception): pass\n", "issue": "support@gittip.com still linked several places\nShould be support@gratipay.com, right? ;-)\n\n", "before_files": [{"content": "\"\"\"\nThis module contains exceptions shared across application code.\n\"\"\"\n\nfrom __future__ import print_function, unicode_literals\n\n\nclass ProblemChangingUsername(Exception):\n    def __str__(self):\n        return self.msg.format(self.args[0])\n\nclass UsernameIsEmpty(ProblemChangingUsername):\n    msg = \"You need to provide a username!\"\n\nclass UsernameTooLong(ProblemChangingUsername):\n    msg = \"The username '{}' is too long.\"\n\nclass UsernameContainsInvalidCharacters(ProblemChangingUsername):\n    msg = \"The username '{}' contains invalid characters.\"\n\nclass UsernameIsRestricted(ProblemChangingUsername):\n    msg = \"The username '{}' is restricted.\"\n\nclass UsernameAlreadyTaken(ProblemChangingUsername):\n    msg = \"The username '{}' is already taken.\"\n\n\nclass ProblemChangingNumber(Exception):\n    def __str__(self):\n        return self.msg\n\nclass HasBigTips(ProblemChangingNumber):\n    msg = \"You receive tips too large for an individual. Please contact support@gittip.com.\"\n\n\nclass TooGreedy(Exception): pass\nclass NoSelfTipping(Exception): pass\nclass NoTippee(Exception): pass\nclass BadAmount(Exception): pass\nclass UserDoesntAcceptTips(Exception): pass\n\nclass FailedToReserveUsername(Exception): pass\n\nclass NegativeBalance(Exception):\n    def __str__(self):\n        return \"Negative balance not allowed in this context.\"\n\nclass NotWhitelisted(Exception): pass\nclass NoBalancedCustomerHref(Exception): pass\n", "path": "gratipay/exceptions.py"}], "after_files": [{"content": "\"\"\"\nThis module contains exceptions shared across application code.\n\"\"\"\n\nfrom __future__ import print_function, unicode_literals\n\n\nclass ProblemChangingUsername(Exception):\n    def __str__(self):\n        return self.msg.format(self.args[0])\n\nclass UsernameIsEmpty(ProblemChangingUsername):\n    msg = \"You need to provide a username!\"\n\nclass UsernameTooLong(ProblemChangingUsername):\n    msg = \"The username '{}' is too long.\"\n\nclass UsernameContainsInvalidCharacters(ProblemChangingUsername):\n    msg = \"The username '{}' contains invalid characters.\"\n\nclass UsernameIsRestricted(ProblemChangingUsername):\n    msg = \"The username '{}' is restricted.\"\n\nclass UsernameAlreadyTaken(ProblemChangingUsername):\n    msg = \"The username '{}' is already taken.\"\n\n\nclass ProblemChangingNumber(Exception):\n    def __str__(self):\n        return self.msg\n\nclass HasBigTips(ProblemChangingNumber):\n    msg = \"You receive tips too large for an individual. Please contact support@gratipay.com.\"\n\n\nclass TooGreedy(Exception): pass\nclass NoSelfTipping(Exception): pass\nclass NoTippee(Exception): pass\nclass BadAmount(Exception): pass\nclass UserDoesntAcceptTips(Exception): pass\n\nclass FailedToReserveUsername(Exception): pass\n\nclass NegativeBalance(Exception):\n    def __str__(self):\n        return \"Negative balance not allowed in this context.\"\n\nclass NotWhitelisted(Exception): pass\nclass NoBalancedCustomerHref(Exception): pass\n", "path": "gratipay/exceptions.py"}]}