BCE0044 Error - expecting :, found '='

Doing my head in, please help me...am close to punching my computer screen. It's such a simple thing. All I want is a checkbox to store a boolean for gravity, if it's checked then store gravity as 10.0.

class CharacterMotorMovement {

 // The maximum horizontal speed when moving
 var maxForwardSpeed : float = 10.0;
 var maxSidewaysSpeed : float = 10.0;
 var maxBackwardsSpeed : float = 10.0;
 
 // Curve for multiplying speed based on slope (negative = downwards)
 var slopeSpeedMultiplier : AnimationCurve = AnimationCurve(Keyframe(-90, 1), Keyframe(0, 1), Keyframe(90, 0));
 
 // How fast does the character change speeds?  Higher is faster.
 var maxGroundAcceleration : float = 30.0;
 var maxAirAcceleration : float = 20.0;
 
 var useGravity : boolean;
 var gravity : float = 0.0;
 
 var maxFallSpeed : float = 20.0;
 
 if(useGravity){
         gravity = 10.0;}
 // For the next variables, @System.NonSerialized tells Unity to not serialize the variable or show it in the inspector view.
 // Very handy for organization!

 // The last collision flags returned from controller.Move
 @System.NonSerialized
 var collisionFlags : CollisionFlags; 

 // We will keep track of the character's current velocity,
 @System.NonSerialized
 var velocity : Vector3;
 
 // This keeps track of our current velocity while we're not grounded
 @System.NonSerialized
 var frameVelocity : Vector3 = Vector3.zero;
 
 @System.NonSerialized
 var hitPoint : Vector3 = Vector3.zero;
 
 @System.NonSerialized
 var lastHitPoint : Vector3 = Vector3(Mathf.Infinity, 0, 0);

}