code: def get(self, property_name=None, environment_variable=None, configuration_option=None, default=None):
          
          if self.overrides.get(property_name) is not None:
              return self.overrides[property_name]
          elif environment_variable and self.environment.get(environment_variable):
              return self.environment[environment_variable]
          elif self.configuration.get(configuration_option) is not None:
              return self.configuration[configuration_option]
          else:
              return default
docs: Internal shortcut to get a configuration option's value.
  
          :param property_name: The name of the property that users can set on
                                the :class:`Config` class (a string).
          :param environment_variable: The name of the environment variable (a
                                       string).
          :param configuration_option: The name of the option in the
                                       configuration file (a string).
          :param default: The default value.
          :returns: The value of the environment variable or configuration file
                    option or the default value.