Rewrite the following algorithm using pseudocode.
```
ALGORITHM simpleSum(n)
// calculates the sum of the first n natural numbers

DECLARE sum: INTEGER
DECLARE number: INTEGER

SET sum TO 0
SET number TO 0

WHILE number < n DO
    sum = sum + number
    number = number + 1
END WHILE

RETURN sum
```
function simpleSum(n: INTEGER)
// calculates the sum of the first n natural numbers
var sum, number: INTEGER
sum := 0
number := 0

while number < n do
  sum := sum + number
  number := number + 1
end while

return sum
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:
Rewrite the following algorithm using pseudocode.

### Input:
function simpleSum(n: INTEGER)
// calculates the sum of the first n natural numbers
var sum, number: INTEGER
sum := 0
number := 0

while number < n do
  sum := sum + number
  number := number + 1
end while

return sum

### Response:
```
ALGORITHM simpleSum(n)
// calculates the sum of the first n natural numbers

DECLARE sum: INTEGER
DECLARE number: INTEGER

SET sum TO 0
SET number TO 0

WHILE number < n DO
    sum = sum + number
    number = number + 1
END WHILE

RETURN sum
```