         }
     }
     
+    @discardableResult
     public func fillParent() -> (left: LALayoutConstraint, right: LALayoutConstraint, width: LALayoutConstraint, height: LALayoutConstraint) {
         return (left: self.setLeft.addToSuperview(), right: self.setRight.addToSuperview(), width: self.setWidth.addToSuperview(), height: self.setHeight.addToSuperview())
     }
     
+    @discardableResult
     public func fillView(_ view: UIView) -> (left: LALayoutConstraint, right: LALayoutConstraint, width: LALayoutConstraint, height: LALayoutConstraint) {
         return (left: self.setLeft.ofView(view).addToSuperview(), right: self.setRight.ofView(view).addToSuperview(), width: self.setWidth.ofView(view).addToSuperview(), height: self.setHeight.ofView(view).addToSuperview())
     }
     
+    @discardableResult
     public func sizeOfParent() -> (width: LALayoutConstraint, height: LALayoutConstraint) {
         return (width: self.setWidth.addToSuperview(), height: self.setHeight.addToSuperview())
     }
     
+    @discardableResult
     public func sizeOfView(_ view: UIView) -> (width: LALayoutConstraint, height: LALayoutConstraint) {
         return (width: self.setWidth.ofView(view).addToSuperview(), height: self.setHeight.ofView(view).addToSuperview())
     }
     
+    @discardableResult
     public func centerInParent() -> (centerX: LALayoutConstraint, centerY: LALayoutConstraint) {
         return(centerX: self.setCenterX.addToSuperview(), centerY: self.setCenterY.addToSuperview())
     }
     
+    @discardableResult
     public func centerInView(_ view: UIView) -> (centerX: LALayoutConstraint, centerY: LALayoutConstraint) {
         return(centerX: self.setCenterX.ofView(view).addToSuperview(), centerY: self.setCenterY.ofView(view).addToSuperview())
     }

        - returns: The layout constraint.
    */
    
    public func addToSuperview() -> LALayoutConstraint {
        if let view = firstItem as? UIView {
            if let superview = view.superview {

        - returns: The layout constraint.
    */
    
    @discardableResult
    public func addToView(_ view: UIView) -> LALayoutConstraint {
        view.addConstraint(self)
        return self
