Calling 1 out of 2 expressions randomly

Hi, I used an expression that will move a character to the left or right depending as time moves forward. The character moves left if the slider control number is negative or the character will move right if the slider controller is a positive number.

However, I want to call an expression randomly at the beginning of the scene so that the character will move either left or right randomly depending on which out of the two expression it chose at random. Maybe this can be done with seedRandom() because it'll only choose one random number without switching it every frame?

Here is my current expression:

right = (value)+value*(time/thisComp.layer("Adjustment Layer 2").effect("Slider Control")("Slider"));

left = (value)+value*(time/thisComp.layer("Adjustment Layer 2").effect("Slider Control 2")("Slider"));

[left[0],value[1]];

Basically, I want the the expression to pull out the variable "left" or "right" randomly.

Is this possible?