What this quote mean tap at the pane quick sharp its from by Robert Browning?

In the context of the poem “The Pied Piper of Hamelin,” the quote "Tap at the pane, quick sharp" means that the rats are hurriedly and excitedly knocking at the windowpane, communicating a sense of urgency and impatience. This quote helps to convey the rats’ eagerness to follow the Pied Piper and highlights their desperation to be led away from Hamelin.