Bitwise MINUS the value of the specified rhs array from the value of this array (retaining the results), and return a non‐`const` reference to this object. The length of the result will be the maximum of the lengths of this object and rhs. If length() > rhs.length(), the unmatched most‐significant bits in this array are left unchanged; otherwise, any high‐order bits of the result that were not present in this object prior to the operation will be set to 0. Note that a ‐= b; will result in the same value of a as a = a ‐ b; and if a and b are the same length, a ‐= b; will result in the same value of a as a &= ~b; or a = a & ~b;.