x <= y.
Like all other FExpr operators, the less-than-or-equal operator is
elementwise: it produces a column where each element is the result of
x[i] <= y[i].
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 less-than-or-equal operator can be applied to columns of any type,
and the types of
y are allowed to be different. In the
latter case the columns will be converted into a common stype before the
The arguments must be either
FExprs, or expressions that can be
An expression that evaluates
x <= y. The produced column will