Foreshadowing

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Foreshadowing
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Foreshadowing

• The simplest form of foreshadowing is by
  mentioning something that will be later used in
  the story. Usually, it is mentioned in passing or
  described as part of a set of seemingly
  unimportant things. The best example is that of
  Chekhov's gun when a certain setting is
  described, it is mentioned that a loaded gun is
  hanging on a wall. Much later on, this gun is
  taken off the wall and fired.
• To draw the reader's attention to the otherwise
  subtle foreshadowing element, writers may often
  make repeated references to the object throughout
  the story.

Source wikipedia