Update dict from any environment variables that have a given prefix.

        The common prefix is removed when converting the variable names to
        dictionary keys. For example, if the following environment variables
        were set::

            MY_APP_SETTING1=foo
            MY_APP_SETTING2=bar

        Then calling ``.update_from_env_namespace('MY_APP')`` would be
        equivalent to calling
        ``.update({'SETTING1': 'foo', 'SETTING2': 'bar'})``.

        :arg namespace: Common environment variable prefix.
        :type env_var: :py:class:`str`

def update_from_env_namespace(self, namespace):
        """
        Update dict from any environment variables that have a given prefix.

        The common prefix is removed when converting the variable names to
        dictionary keys. For example, if the following environment variables
        were set::

            MY_APP_SETTING1=foo
            MY_APP_SETTING2=bar

        Then calling ``.update_from_env_namespace('MY_APP')`` would be
        equivalent to calling
        ``.update({'SETTING1': 'foo', 'SETTING2': 'bar'})``.

        :arg namespace: Common environment variable prefix.
        :type env_var: :py:class:`str`
        """
        self.update(ConfigLoader(os.environ).namespace(namespace))