represents a function to be applied whenever the symbol symb gets a new value.


  • To use , you first need to load the Experimental Functions Package using Needs["Experimental`"].
  • The assignment specifies that whenever symb gets a new value val, the expression should be evaluated.
  • If the value of symb is cleared, is evaluated.
  • takes account of all ways that the value of a symbol can be changed, not just Set.
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