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/*  LOGARITHMIC ARRAYS.

    An array extends from 0 to 2**Size - 1, where Size is a multiple of 2.
    Note that 2**Size = 1<<Size.

    External interface.

    new_array(A) returns a new empty array A.

    is_array(A) checks whether A is an array.

    aref(Index,Array,Element) unifies Element with Array[Index],
	or fai


















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































