SHIFT array-name [ , variable-name ]

   Synopsis:
      Removes the first value in an array

   Notes:
      This statement only works on one-dimensional arrays (stacks). If you use
         it with a multi-dimensional array, you'll get an error.

      Removes the first cell in the array, reducing (for example) an array of
         ten values to an array of nine.
      If the optional scalar variable name is specified, the value is assigned
         to it. Otherwise, the value is discarded. Both the array and scalar
         variables must be of the same type (both strings, or both numeric).         
      If you try to SHIFT an empty array, the value assigned to the scalar
         variable will be either an empty string, or 0.

   Compatibility:
      Since Axbasic v1.4
      
   Examples:
      DATA "foo", "bar", "baz"
      
      DIM stuff$ (3)
      FOR a = 1 TO 3
         READ stuff$ (a)
      NEXT a

      ! Remove and display "foo"
      SHIFT stuff$, name$
      PRINT name$
