anchor.diff:  Display the contents of the current buffer.
   
   This only displays the buffer of an incomplete expression. Once the
  -expression is complete, the buffer is rest. The prompt will update to
  +expression is complete, the buffer is reset. The prompt will update to
   show the size of the current buffer as well.
   
   [[GroovyShell-Example]]
  
positive.code: ----
  groovy:000> :grab 'com.google.guava:guava:19.0'
  groovy:000> import com.google.common.collect.BiMap
  ===\> com.google.common.collect.BiMap
  ----
  
  This command can be given at any time to add new dependencies.
  
negative.code: 
  ----
  groovy:000> def x = 3
  ===> 3
  groovy:000> x
  ===> 3
  ----
  
  It's especially useful for copy&pasting code from tutorials etc. into the running session.
  