code: func (x *Dec) Unscaled() (u int64, ok bool) {
  	u = x.unscaled.Int64()
  	var i big.Int
  	ok = i.SetInt64(u).Cmp(&x.unscaled) == 0
  	return
  }
docs: // Unscaled returns the unscaled value of x for u and true for ok when the
  // unscaled value can be represented as int64; otherwise it returns an undefined
  // int64 value for u and false for ok. Use x.UnscaledBig().Int64() to avoid
  // checking the validity of the value when the check is known to be redundant.