Hi guys,

Just looking for some clarification regarding “Reggie’s Linear Regression” Off-Platform Project found here:

https://www.codecademy.com/courses/learn-python-3/informationals/python3-reggies-linear-regression

Under the calculate_error function, I don’t understand the syntax:

```
def calculate_error(m, b, point):
x_point, y_point = point
```

- When I printed the type, I realised it was a tuple, but why is it not enclosed in parentheses ()?
- I also thought assignment is usually performed left to right so does this line assign both x_point and y_point to the tuple point?

In an attempt to understand it better, I inverted the line i.e.

```
def calculate_error(m, b, point):
point = x_point, y_point
```

but then the following testing of the function no longer worked correctly.

To get around this I rewrote it as follows:

```
def calculate_error(m, b, point):
x_point = point[0]
y_point = point[1]
```

but I do not view this as good practice, more of a hack per say.

In short, could someone please clarify the differences:

- why/how is it a tuple if not enclosed in ()?
- why does the line not work if inverted and what is the difference?

Please excuse my formatting, first post. I’ll get the hang of it!

Many thanks.