anchor.diff:   | postfix_expression '.' Pure_decimal_digits                     # 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
  +// self.addTarget(self, action: #selector(nameOfAction(_:)))
  + | postfix_expression '(' argument_names ')'                      # explicit_member_expression4
    | postfix_expression '.' 'self'                                  # postfix_self_expression
    | postfix_expression '.' 'dynamicType'                           # dynamic_type_expression
    | postfix_expression '[' expression_list ']'                     # subscript_expression
  
positive.code:  * Converted from Apple's doc, http://tinyurl.com/n8rkoue, to ANTLR's
   * meta-language.
   */
  grammar Swift; // 2.1
  
  top_level : statement* EOF ;
  
  
negative.code: // GRAMMAR OF A TRY EXPRESSION
  
  try_operator : 'try' | 'try' '?' | 'try' '!' ;
  try_operator : 'try' '?' | 'try' '!' | 'try' ;
  
  // GRAMMAR OF A BINARY EXPRESSION
  
  