# selectPair(valueSelector, keySelector[, arg])

Projects each element of a sequence into a new form including keys.

## Syntax

**Parameters**
*valueSelector*
Type: function(value, key, arg)

*keySelector*
Type: function(value, key, arg)

*arg*
An external argument.

**Return Value**
An iteratable object whose elements are the result of invoking the transform function on each element of source.

## Examples

var squares = $range(1, 11).selectPair("$ * $", "$");
squares.each("document.writeln('The square of ' + $$ + ' is ' + $)");
/*
This code produces the following output:
The square of 1 is 1
The square of 2 is 4
The square of 3 is 9
The square of 4 is 16
The square of 5 is 25
The square of 6 is 36
The square of 7 is 49
The square of 8 is 64
The square of 9 is 81
The square of 10 is 100
*/