docs: @Nonnull
    public static AbstractJSExpression plus (@Nonnull final IJSExpression aLeft, @Nonnull final IJSExpression aRight)
    {
      // Some optimizations
      if (aLeft instanceof JSStringLiteral && aRight instanceof JSStringLiteral)
        return new JSStringLiteral (((JSStringLiteral) aLeft).getContainedString () +
                                    ((JSStringLiteral) aRight).getContainedString ());
      if (aLeft instanceof AbstractJSAtomNumeric && aRight instanceof AbstractJSAtomNumeric)
        return ((AbstractJSAtomNumeric) aLeft).numericPlus ((AbstractJSAtomNumeric) aRight);
  
      return new JSOpBinary (aLeft, "+", aRight);
    }