Add the specified rhs to the value of the specified lhs as described by IEEE-754 and return the result.
* If lhs is signaling NaN, then store the value of the macro EDOM into errno and return a NaN. * Otherwise if lhs object is NaN, then return a NaN. * Otherwise if lhs is infinity, then return infinity. * Otherwise if the sum of lhs and rhs has an absolute value that is larger than std::numeric_limits<Decimal32>::max() then store the value of the macro ERANGE into errno and return infinity with the same sign as that result. * Otherwise return the sum of rhs and the number represented by lhs.