code: def declare_base(erroName=True):
      
      if erroName:
          class Base(Exception):
              def __str__(self):
                  if len(self.args):
                      return "%s: %s" % (self.__class__.__name__, self.args[0])
                  else:
                      return "%s: %s" % (self.__class__.__name__, self.default)
      else:
          class Base(Exception):
              def __str__(self):
                  if len(self.args):
                      return "%s" % self.args[0]
                  else:
                      return "%s" % self.default
      return Base
docs: Create a Exception with default message.
      
      :param errorName: boolean, True if you want the Exception name in the 
        error message body.