anchor.diff:   | continue_statement
    | fallthrough_statement
    | return_statement
  + | throw_statement
    ;
   
   // GRAMMAR OF A BREAK STATEMENT
  
positive.code: 
  identifier : Identifier | context_sensitive_keyword ;
  
  keyword : 'convenience' | 'class' | 'deinit' | 'enum' | 'extension' | 'func' | 'import' | 'init' | 'let' | 'protocol' | 'static' | 'struct' | 'subscript' | 'typealias' | 'var' | 'break' | 'case' | 'continue' | 'default' | 'do' | 'else' | 'fallthrough' | 'if' | 'in' | 'for' | 'return' | 'switch' | 'where' | 'while' | 'as' | 'dynamicType' | 'is' | 'new' | 'super' | 'self' | 'Self' | 'Type' ;
  
  context_sensitive_keyword :
   'associativity' | 'didSet' | 'get' | 'infix' | 'inout' | 'left' | 'mutating' | 'none' |
   'nonmutating' | 'operator' | 'override' | 'postfix' | 'precedence' | 'prefix' | 'right' |
   'set' | 'unowned' | 'unowned(safe)' | 'unowned(unsafe)' | 'weak' | 'willSet'
   ;
  
  Operator
    : Operator_head Operator_character*
    | '..' ('.'|Operator_character)*
    ;
  
  Operator_head
    : '/' | '=' | '\\' | '-' | '+' | '!' | '*' | '%' | '<' | '>' | '&' | '|' | '^' | '!' | '.'
    | [\u00A1-\u00A7]
    | [\u00A9\u00AB\u00AC\u00AE]
    | [\u00B0-\u00B1\u00B6\u00BB\u00BF\u00D7\u00F7]
    | [\u2016-\u2017\u2020-\u2027]
    | [\u2030-\u203E]
    | [\u2041-\u2053]
    | [\u2055-\u205E]
    | [\u2190-\u23FF]
    | [\u2500-\u2775]
    | [\u2794-\u2BFF]
    | [\u2E00-\u2E7F]
    | [\u3001-\u3003]
    | [\u3008-\u3030]
    ;
  
  Operator_character
    : Operator_head
    | [\u0300–\u036F]
    | [\u1DC0–\u1DFF]
    | [\u20D0–\u20FF]
    | [\uFE00–\uFE0F]
    | [\uFE20–\uFE2F]
    //| [\uE0100–\uE01EF]  ANTLR can't do >16bit char
    ;
  
  Dot_operator_head
    : '..'
    ;
  
  Identifier : Identifier_head Identifier_characters?
   | '`' Identifier_head Identifier_characters? '`'
  
negative.code: Binary_literal : '0b' Binary_digit Binary_literal_characters? ;
  fragment Binary_digit : [01] ;
  fragment Binary_literal_character : Binary_digit | '_'  ;
  fragment Binary_literal_characters : Binary_literal_character+ ;
  
  Octal_literal : '0o' Octal_digit Octal_literal_characters? ;
  fragment Octal_digit : [0-7] ;
  