anchor.diff:  |LIST 100+ |Lists line 100 and the next 20 lines.
   |==========
   
  +LOAD
  +~~~~
  +
  +Loads a stored program into memory.
  +Sorts statements by line number.
  +Clears the current program prior to loading the new one.
  +
  +Syntax:	LOAD filename
  +
  +The 'filename' argument may be enclosed in quotes.
  +Quotes are necessary when the name contains a space character.
  +
  +NEW
  +~~~
  +
  +Clears the current program.
  +Does not ask to save a loaded program.
  +
  +Syntax:	NEW
  +
   PRETTY
   ~~~~~~
   
  
positive.code: 
  The second phase executes statements, starting with the lowest-numbered statement and following the path of execution.
  
  TRACE
  ~~~~~
  
  
negative.code: READ displays the values read.
  LET displays the new value assigned.
  IF displays the two values, the operator, and the result ('true' or 'false').
  
  Variables
  ---------
  