Method range_check

chapter21/src/main/java/com/seaofnodes/simple/Ary.java:203–206

( int i )

    }

    private void range_check( int i ) {
        if( i < 0 || i>=_len )
            throw new ArrayIndexOutOfBoundsException(""+i+" >= "+_len);
    }

    // Note that the hashCode() and equals() are not invariant to changes in the
    // underlying array.  If the hashCode() is used (e.g., inserting into a