anchor.diff:      ;
   
   packageHeader
  -    : 'package' identifier semi?
  +    : ('package' identifier semi?)?
       ;
   
   importList
  
positive.code:     | assignableExpression assignmentAndOperator NL* expression
      ;
  
  expression
      : disjunction
      ;
  
negative.code:     | expression)
      ;
  
  label
      : IdentifierAt NL*
      ;
  
  controlStructureBody
      : block
      | statement
      ;
  
  block
      : '{' NL* statements NL* '}'
      ;
  
  loopStatement
      : forStatement
      | whileStatement
      | doWhileStatement
      ;
  
  forStatement
      : 'for' NL* '(' annotation* (variableDeclaration | multiVariableDeclaration) IN expression ')' NL* controlStructureBody?
      ;
  
  whileStatement
      : 'while' NL* '(' expression ')' NL* controlStructureBody
      | 'while' NL* '(' expression ')' NL* ';'
      ;
  
  doWhileStatement
      : 'do' NL* controlStructureBody? NL* 'while' NL* '(' expression ')'
      ;
  
  assignment
  