Oh, sorry. lerp is a system expression.
From the manual: "lerp(a, b, x) Linear interpolation of a to b by x. Calculates a + x * (b - a)."
So for smooth camera tracking, you might try System / Scroll To Position and setting X to lerp(scrollx, player.x, 0.05) and Y to lerp(scrolly, player.y, 0.05). That third value in each, (0.05 in this example) changes how fast it'll scroll. The bigger the number, the snappier it'll be.