2. Safemathsafemath gem / library - safe math operations (with overflow 'n' underflow protection) on signed and unsigned integer number types (U8, U16, U32, U64, U256, I8, I16, I32, I64, I256)
3. units-timeunits-time library / gem - units of time (in epoch time) incl. seconds, minutes, hours, days, weeks, fortnights, years and more