Based on the passage below:
"After Twenty Years" is a classic O. Henry story.
It is brief, evocative, and its impact is heightened by the author's masterful use of a twist ending.
In this case, the story's power comes from the fact that the first policeman who encounters "Silky" Bob is actually Jimmy Wells, who is there, presumably, to keep the promise he made to his old friend twenty years earlier.
Now take some time to break down the story's elements and understand the details that O. Henry uses to foreshadow the ending and make the story enjoyable.
Who is really "Silky" Bob?