Page Comparison

...

forEach() is like every other function in that it returns a value. 

• Its return value is a list containing the last statement executed in the last each iteration.
• All the $-variables used in the call to forEach() keep their values between iterations.
• All the $-variables used in the call to forEach() will be available after it has returned.

...

forEach($number, $numberList, 

   $currentValue = $number*2

),

Returns [2,4,6,8,10,12,14,16,18,20], as forEach() returns the value of the final expression to be evaluated in its final each iteration.

do(
  forEach($number, $numberList,  
    $sumOfNumbers = $sumOfNumbers + $number
  ),
  $sumOfNumbers
)

Returns 55. The forEach will return the value at each iteration ([1, 3, 6, 10, 15, 21, 28, 36, 45, 55, as the variable $sumOfNumbers persists in-between forEach iterations]), the do then returns the final value of $sumOfNumbers.

Detailed example: (step-by-step)

...