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 The ‘dotimes’ Macro
 -------------------
 
 The ‘dotimes’ macro is similar to ‘dolist’, except that it loops a
 specific number of times.
 
    The first argument to ‘dotimes’ is assigned the numbers 0, 1, 2 and
 so forth each time around the loop, and the value of the third argument
 is returned.  You need to provide the value of the second argument,
 which is how many times the macro loops.
 
    For example, the following binds the numbers from 0 up to, but not
 including, the number 3 to the first argument, NUMBER, and then
 constructs a list of the three numbers.  (The first number is 0, the
 second number is 1, and the third number is 2; this makes a total of
 three numbers in all, starting with zero as the first number.)
 
      (let (value)      ; otherwise a value is a void variable
        (dotimes (number 3 value)
          (setq value (cons number value))))
 
      ⇒ (2 1 0)
 
 ‘dotimes’ returns ‘value’, so the way to use ‘dotimes’ is to operate on
 some expression NUMBER number of times and then return the result,
 either as a list or an atom.
 
    Here is an example of a ‘defun’ that uses ‘dotimes’ to add up the
 number of pebbles in a triangle.
 
      (defun triangle-using-dotimes (number-of-rows)
        "Using `dotimes', add up the number of pebbles in a triangle."
      (let ((total 0))  ; otherwise a total is a void variable
        (dotimes (number number-of-rows total)
          (setq total (+ total (1+ number))))))
 
      (triangle-using-dotimes 4)
 

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