Sequence node: Do this, Then this, Then This, Then This
As soon as the last thing in the previous Then line executes the next sequence Then fires.
Take the following Function.
As soon as Function X is called Function Y is immediately called after.
Then immediately after that Function Z, then the Return.
Now If Function X has a return value it will be allowed to completely finish and return its value before moving to Function Y.
The same applies to Setting variables.
I typically calculate all my parameters on the first and second Thens before doing all the meat and potatoes functionality.
Sequences work just like Vertical C++ code
Then 0 = Line 1;
Then 1 = Line 2;
etc.