Is the theme 'selfishness' from the last leaf by o Henry explicit or implied?

The theme of selfishness in "The Last Leaf" by O. Henry is primarily implied rather than explicit. Through the characters' actions and motivations, readers can infer themes related to selfishness, such as Johnsy's initial self-absorption and Sue's selflessness. The story's focus on sacrifice and friendship also underscores the implied theme of selfishness.