operator-pow

The power operator binds more tightly than unary operators on its left; it binds less tightly than unary operators on its right. The syntax is:

power ::= [ primary][1] [“**” [u_expr][2]]

Thus, in an unparenthesized sequence of power and unary operators, the operators are evaluated from right to left (this does not constrain the evaluation order for the operands).

The power operator has the same semantics as the built-in pow function, when ca