anchor.diff:       e.replace(oldElement, newElement)
   
     ###**
  -  Defines a named transition.
  +  Defines a named transition that [morphs](/up.element) from one element to another.
  +
  +  \#\#\# Example
   
     Here is the definition of the pre-defined `cross-fade` animation:
   
  
positive.code:   are completed.
  
    Animations are completed by jumping to the last animation frame instantly.
  
    Does nothing if there are no animation to complete.
    
  
negative.code:       var warning = document.querySelector('.warning')
        warning.style.opacity = 0
        up.animate(warning, { opacity: 1 })
  
    CSS properties must be given in `kebab-case`, not `camelCase`.
  
    \#\#\# Multiple animations on the same element
  
  