anchor.diff:      ;
       
   granteeIdentifiedBy
  -    : userName (COMMA userName)* IDENTIFIED BY STRING (COMMA STRING)*
  +    : userNames IDENTIFIED BY STRING (COMMA STRING)*
       ;
       
   grantObjectPrivilegeClause
  
positive.code:     : objectPrivilege (COMMA objectPrivilege)* onObjectClause
      FROM grantees
      (CASCADE CONSTRAINTS | FORCE)?
      ;
negative.code:     ;
      
  grantRolesToPrograms
      : roleNames TO programUnits
      ;
  
  programUnits
      : programUnit (COMMA programUnit)*
      ;
      
  programUnit
  