Returns flow argument, as provided with sitegate decorators
           or attribute set as a flow class attribute or default.

def get_arg_or_attr(self, name, default=None):
        """Returns flow argument, as provided with sitegate decorators
           or attribute set as a flow class attribute or default."""
        if name in self.flow_args:
            return self.flow_args[name]
        try:
            return getattr(self, name)
        except AttributeError:
            return default