I tried this, I also saw something like it on the wiki, but it shows a red line and doesn't work.
AnimTrack:AdjustSpeed(float speed = 3)
The thing in the parenthesis would be a number, like this:
AnimTrack:AdjustSpeed(3)
float
indicates what data type it is (a floating point number. ex: 2.3, 3, 6.76). speed
indicates what the number is (speed
would indicate that it changes the speed of the animation). Hope this helped!