Return true if lhs is ordered before rhs or they are equal.
Declared in <bdlb_nullablevalue.h>
template<
class LHS_TYPE,
class RHS_TYPE>
bool
operator<=(
std::optional<LHS_TYPE> const& lhs,
NullableValue<RHS_TYPE> const& rhs)
requires requires {
{ *lhs <= *rhs } -> NullableValue_ConvertibleToBool;
};