anchor.diff:  /* The ASP-Core-2 grammar in ANTLR v4 based on
    * https://www.mat.unical.it/aspcomp2013/files/ASP-CORE-2.01c.pdf
    * (sections 4 and 5, pages 10-12).
  - * It is extended a bit to parse widespread syntax used by gringo/clasp,
  - * see productions "gringo_range" and "gringo_sharp".
  + * It is extended a bit to parse widespread syntax (e.g. used by gringo/clasp).
    */
   
   program : statements? query?;
  
positive.code: 
  interval : lower = (NUMBER | VARIABLE) DOT DOT upper = (NUMBER | VARIABLE); // NOT Core2 syntax, but widespread
  
  external_atom : MINUS? AMPERSAND ID (SQUARE_OPEN output = terms SQUARE_CLOSE)? (PAREN_OPEN input = terms PAREN_CLOSE)?;
  
  gringo_sharp : SHARP ~(DOT)* DOT; // NOT Core2 syntax, but widespread, matching not perfect due to possible earlier dots
  
  
negative.code: 
  variable_term : VARIABLE | ANONYMOUS_VARIABLE;
  
  answer_set : CURLY_OPEN classical_literal? (COMMA classical_literal)* CURLY_CLOSE;
  
  answer_sets: answer_set*;