Get value.

def get(self, name, default=None):
        """Get value."""
        default = default if default is not None else self.default
        try:
            value = getattr(_settings, name)
        except AttributeError:
            value = os.environ.get(name, default) if self.from_env else default
            # Convert env variable.
            if value != default:
                value = self.env_clean(value)

        return self.validate(name, value)