anchor.diff:     ;
   
   opbinding
  -   : name (',' name)* ':' primary
  +   : name (',' name)* ':' primaries
      ;
   
   expression
  -   : primary
  -   | call '@' primary
  -   | '('expression')'
  +   : primaries
  +   | call '@' primaries
  +   | '(' expression ')'
      | '~' expression
      | '−' expression
      | expression '**' expression
  
positive.code: own_var
     : 'own' decl
     | 'own' idn ':' type_spec ':=' expression
     | 'own' decl (',' decl)* ':=' call ('@' primary)?
     ;
  
  statement
     : decl
     | idn ':' type_spec ':=' expression
     | decl (',' decl)* ':=' call ('@' primary)?
     | idn (',' idn)* ':=' call ('@' primary)?
     | idn (',' idn)* ':=' expression (',' expression)*
     | primary '.' name ':=' expression
     | primary expression? ':=' expression
     | call ('@' primary)?
     | 'fork' call
     | 'seize' expression 'do' body 'end'
     | 'pause'
  
negative.code:    | expression 'cor' expression
     ;
  
  primaries
     : primary (('.' name) | expression (',' expression)*)*
     ;
  
  primary
     : entities
     ;
  
  call
     : primaries '(' ((expression (',' expression)*))? ')'
     ;
  
  entities
     : entity (('.' name) | expression)*
     ;
  
  entity
  