code: function createUnits(conversions, withNames=false) {
      const result = {};
      conversions.forEach(c => c.names.forEach(name =>
          result[unitToLower(normalizeUnitName(name))] = {
              name: c.names[0],
  
              prefix: c.prefix,
  
              scale: c.scale,
              toBase: c.toBase,
              fromBase: c.fromBase,
  
              names: withNames ? c.names : null
          }
      ));
      return result;
  }
docs: Map a list of conversions into an object where each name is represented
  as a key.