class HttpForbidden(Exception):
  pass

class HttpNotFound(Exception):
  pass


class ModelException(Exception):
  pass

class ModelDeny(ModelException):
  pass

class ModelWrongData(ModelException):
  def __init__(self, messages = None):
    if messages is None:
      messages = list()
    if type(messages) is str:
      messages = [messages]
    assert(type(messages) is list)
    self.messages = messages


class ActionError(Exception):
  def __init__(self, messages = None):
    if messages is None:
      messages = list()
    if type(messages) is str:
      messages = [messages]
    assert(type(messages) is list)
    self.messages = messages