anchor.diff:     ;
   
   variable_name
  -   : '*'? IDENTIFIER ('=' expression2)?
  +   : '*'* IDENTIFIER ('=' expression2)?
      ;
   
   constant
  
positive.code: statement
     : expression2 ';'
     | cond
     | while
     | do_while
     | for
     | switch
     | case
     | default
     | block
     | foreach
     | break
     | continue
     | ';'
     ;
  
  
negative.code:    : '([' (expression ':' expression (',' expression ':' expression)*)? ','? '])'
     ;
  
  
  program_specifier
     :
  