  Creates and activates a constraint that defines leftAnchor's attribute as less than or equal to rightAnchor's attribute plus a constant offset.
 
  - parameter leftAnchor: A layout anchor from a `UIView`, `NSView`, or `UILayoutGuide` object.
- - parameter pair:       A tuple containing a layout anchor of compatible type and a constant offset.
+ - parameter rightAnchor: A layout anchor from a `UIView`, `NSView`, or `UILayoutGuide` object of the same type.
+ - parameter constant:  The offset constant for this relationship.
 
  - returns: The new constraint.
  */

 Creates and activates a constraint that defines a size attribute as equal to another size attribute plus a constant offset.

 - parameter leftAnchor: A dimension anchor from a `UIView`, `NSView`, or `UILayoutGuide` object.
 - parameter rest:       A tuple containing an anchor and constant value
 - paramater rightAnchor: A dimension anchor of same type from a `UIView`, `NSView`, or `UILayoutGuide` object.
 - parameter constant:   The offset constant for this relationship.


 Creates and activates a constraint that sets a constant size for the attribute associated with a dimension anchor.

 - parameter leftDimension:  A dimension anchor from a `UIView`, `NSView`, or `UILayoutGuide` object.
 - parameter constant:  A constant representing the size of the attribute associated with the dimension anchor.

 - returns: The new constraint.
 */
