code: func (q *Quantity) AsCanonicalBytes(out []byte) (result []byte, exponent int32) {
  	if q.d.Dec != nil {
  		return q.d.AsCanonicalBytes(out)
  	}
  	return q.i.AsCanonicalBytes(out)
  }
docs: // AsCanonicalBytes returns the canonical byte representation of this quantity as a mantissa
  // and base 10 exponent. The out byte slice may be passed to the method to avoid an extra
  // allocation.