anchor.diff:     | ('down' '(' expression ')')
      ;
   
  +invocation
  +   : primary '(' expression (',' expression)* ')'
  +   ;
  +
  +field
  +   : name (',' name)* ':' expression
  +   ;
  +
   idn
      : STRING
      ;
  
positive.code: 
  body
     : equate* statement*
     ;
  
  invocation
     : primary '(' expression (',' expression)* ')'
     ;
  
  field
     : name (',' name)* ':' expression
     ;
  
  expression
  
negative.code:    ;
  
  
  INT
     : [0-9] +
     ;
  
  
  FLOAT
     : [0-9] + '.' [0-9]*
     ;
  
  
  COMMENT
     : ';' ~ [\r\n]* -> skip
     ;
  
  
  