Get the first FunctionAnalysis task in the stack.

        :return: The top function analysis task in the stack, or None if there isn't any.
        :rtype: FunctionAnalysis

def _top_function_analysis_task(self):
        """
        Get the first FunctionAnalysis task in the stack.

        :return: The top function analysis task in the stack, or None if there isn't any.
        :rtype: FunctionAnalysis
        """

        for r in reversed(self._task_stack):
            if isinstance(r, FunctionAnalysis):
                return r
        return None