()                       Grouping

   ((exp1 op1 exp2) op2 exp3)

    The group operator () is used to force an order of evaluation.  For
    example:

        i = 1 + 3 * 5;          # i == 16, * has higher precedence than +
        j = ( 1 + 3 ) * 5;      # j == 20, force 1 + 3