Cannot say when the function is introduced, or if it even is. However, it is a simple function to learn and use, as the documentation will show.

Essentially, *rounding* follows one simple rule:

```
up on 5
down on 4
```

Let’s look at PI as an example:

```
3.1415926...
```

Above there are seven decimal places showing. To reduce it to six, we round *up* on 6 (3.141593). To reduce to five, we round *down* on 2 (3.14159). For four, up on 9 (3.1416), for three, up on 5 (3.142). For two decimal places we round down on 1 (3.14).

This is the exact behavior of the `round()`

function.

Rounding does not remove the decimal point, though.

```
round(pi, 0)
3.0
```

However, 3.0 is equal to 3 in terms of value and magnitude. That’s as close as `round()`

can bring us.

Truth is, mathematically there is no way to tell if a number is truly an integer, since that is a **type**. Allowing for the decimal point zero has to be a given in solving this problem.

We can also use the modulo rule,

```
n % 1 is zero, if n is an integer (or the decimal fraction is zero)
```

When the result is non-zero, then there must be some decimal fraction.

```
print (pi % 1)
0.14159265358979312
```