There is a better way, but it is slightly more complicated but if your going to make neat code then I reccomend using it...
x#=newxvalue(x#,wrapvalue(a#+90),strafespeed)
z#=newxvalue(x#,wrapvalue(a#+90),strafespeed)
newzvalue finds where you need to move in 3d space according to the angle that you are 'facing'. If your at 0 degrees then obviously your only going to travel along the z axis (imagine a graph with axis).
z
 ^ you only travel along the z axis
  at 0 degrees

x



But if you are at an angle then you are going to travel along the x and z axis. You can work this out using sin and cos but these commands do it for you. the first number in the brackets is the position that you are moving from, the second is the angle that you are standing at and the third is the distance you want to move forward.
If you set the angle 90 degrees to one side then you can strafe from side to side.
z
 ^ you travel along the z and
 / x axis at most angles (excluding 0,90,180 and 270)

x



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