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Switch (Conditional operator) Performs one action according to the value of the first argument. If the argument evaluates to 0, the first action is performed; if the argument is 1, the next action is performed, etc. If the value is out of range, no action is performed at all. Takes 2 or more arguments... 1: Numeric expression to evaluate. Rest: List of actions, one of which (at most) will be taken according to the value of the expression.