 &= \sum_{0\leq n <\infty}\sum_{\substack{i_0,\ldots,i_n\in {\ensuremath{\mathsf{c}}\xspace}\\ a_0,\ldots,a_n\in A}}   {{\mathbb P}}(\{T_0=n\}\cap B_{0,0}^{T_0} ~|~ X_0={s''}) f(i_0,\ldots,i_{n},a_0,\ldots,a_{n})