not all code paths return a value and must declare a body for CheckIsValidPosition()

code errors are stemming from the bool CheckIsValidPosition() { Here is the code:

float fall = 0; public float fallSpeed = 1;

 public bool allowRotation = true;
 public bool limitRotation = false;


 // Use this for initialization
 void Start()
 {

 }


 // Update is called once per frame
 void Update()
 {

     CheckUserInput();
 }

 void CheckUserInput()
 {





     if (Input.GetKeyDown(KeyCode.RightArrow))
     {

         transform.position += new Vector3(1, 0, 0);


     }
     else if (Input.GetKeyDown(KeyCode.LeftArrow))
     {

         transform.position += new Vector3(-1, 0, 0);

     }
     else if (Input.GetKeyDown(KeyCode.UpArrow))
     {

         transform.Rotate(0, 0, -90);

     }
     else if (Input.GetKeyDown(KeyCode.DownArrow) || Time.time - fall >= fallSpeed)
     {

         transform.position += new Vector3(0, -1, 0);


         fall = Time.time;

     }

 }

 bool CheckIsValidPosition() { 

}