y are multi-column expressions, then they must have the
same number of columns, and the
** operator will be applied to each
corresponding pair of columns. If either
y are single-column
while the other is multi-column, then the single-column expression
will be repeated to the same number of columns as its opponent.
The power operator can only be applied to numeric columns, and the
resulting column will have stype
float64 in all cases except when both
float32 (in which case the result is also
The arguments must be either
FExprs, or expressions that can be
An expression that evaluates
x ** y.