def from_envvar(self, variable_name, silent=False):
        """Loads a configuration from an environment variable pointing to
        a configuration file.  This is basically just a shortcut with nicer
        error messages for this line of code::

            app.config.from_pyfile(os.environ['YOURAPPLICATION_SETTINGS'])

        :param variable_name: name of the environment variable
        :param silent: set to `True` if you want silent failure for missing
                       files.
        :return: bool. `True` if able to load config, `False` otherwise.
        """
        rv = os.environ.get(variable_name)
        if not rv:
            if silent:
                return False
            raise RuntimeError('The environment variable %r is not set '
                               'and as such configuration could not be '
                               'loaded.  Set this variable and make it '
                               'point to a configuration file' %
                               variable_name)
        return self.from_pyfile(rv, silent=silent)
dataset/ETHPy150Open baseblack/ReproWeb/3rdParty/python/flask/config.py/Config.from_envvar/original