anchor.diff:   | postfix_expression parenthesized_expression? trailing_closure  # function_call_with_closure_expression
    | postfix_expression '.' 'init'                                  # initializer_expression
    | postfix_expression '.' 'init' '(' argument_names ')'           # initializer_expression_with_args
  - | postfix_expression '.' Decimal_literal                     # explicit_member_expression1
  + | postfix_expression '.' Decimal_literal                         # explicit_member_expression1
    | postfix_expression '.' identifier generic_argument_clause?     # explicit_member_expression2
    | postfix_expression '.' identifier '(' argument_names ')'       # explicit_member_expression3
   // This does't exist in the swift grammar, but this valid swift statement fails without it
  
positive.code: dictionary_literal		 : '[' dictionary_literal_items ']' | '[' ':' ']'  ;
  dictionary_literal_items : dictionary_literal_item (',' dictionary_literal_item)* ','? ;
  dictionary_literal_item  : expression ':' expression  ;
  
  // GRAMMAR OF A SELF EXPRESSION
  
  
negative.code: // GRAMMAR OF A CLASS DECLARATION
  
  class_declaration
   : attributes? access_level_modifier? 'final'? 'class' class_name
     generic_parameter_clause? type_inheritance_clause? class_body
   | attributes? 'final' access_level_modifier? 'class' class_name
     generic_parameter_clause? type_inheritance_clause? class_body
   ;
  class_name : identifier ;
  