SOURCE_FILE
  FN
    COMMENT "// format with label break value."
    WHITESPACE "\n"
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "main"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE "\n    "
        EXPR_STMT
          BLOCK_EXPR
            LABEL
              LIFETIME
                LIFETIME_IDENT "'empty_block"
              COLON ":"
            WHITESPACE " "
            STMT_LIST
              L_CURLY "{"
              R_CURLY "}"
        WHITESPACE "\n\n    "
        EXPR_STMT
          BLOCK_EXPR
            LABEL
              LIFETIME
                LIFETIME_IDENT "'block"
              COLON ":"
            WHITESPACE " "
            STMT_LIST
              L_CURLY "{"
              WHITESPACE "\n        "
              EXPR_STMT
                CALL_EXPR
                  PATH_EXPR
                    PATH
                      PATH_SEGMENT
                        NAME_REF
                          IDENT "do_thing"
                  ARG_LIST
                    L_PAREN "("
                    R_PAREN ")"
                SEMICOLON ";"
              WHITESPACE "\n        "
              EXPR_STMT
                IF_EXPR
                  IF_KW "if"
                  WHITESPACE " "
                  CALL_EXPR
                    PATH_EXPR
                      PATH
                        PATH_SEGMENT
                          NAME_REF
                            IDENT "condition_not_met"
                    ARG_LIST
                      L_PAREN "("
                      R_PAREN ")"
                  WHITESPACE " "
                  BLOCK_EXPR
                    STMT_LIST
                      L_CURLY "{"
                      WHITESPACE "\n            "
                      EXPR_STMT
                        BREAK_EXPR
                          BREAK_KW "break"
                          WHITESPACE " "
                          LIFETIME
                            LIFETIME_IDENT "'block"
                        SEMICOLON ";"
                      WHITESPACE "\n        "
                      R_CURLY "}"
              WHITESPACE "\n        "
              EXPR_STMT
                CALL_EXPR
                  PATH_EXPR
                    PATH
                      PATH_SEGMENT
                        NAME_REF
                          IDENT "do_next_thing"
                  ARG_LIST
                    L_PAREN "("
                    R_PAREN ")"
                SEMICOLON ";"
              WHITESPACE "\n        "
              EXPR_STMT
                IF_EXPR
                  IF_KW "if"
                  WHITESPACE " "
                  CALL_EXPR
                    PATH_EXPR
                      PATH
                        PATH_SEGMENT
                          NAME_REF
                            IDENT "condition_not_met"
                    ARG_LIST
                      L_PAREN "("
                      R_PAREN ")"
                  WHITESPACE " "
                  BLOCK_EXPR
                    STMT_LIST
                      L_CURLY "{"
                      WHITESPACE "\n            "
                      EXPR_STMT
                        BREAK_EXPR
                          BREAK_KW "break"
                          WHITESPACE " "
                          LIFETIME
                            LIFETIME_IDENT "'block"
                        SEMICOLON ";"
                      WHITESPACE "\n        "
                      R_CURLY "}"
              WHITESPACE "\n        "
              EXPR_STMT
                CALL_EXPR
                  PATH_EXPR
                    PATH
                      PATH_SEGMENT
                        NAME_REF
                          IDENT "do_last_thing"
                  ARG_LIST
                    L_PAREN "("
                    R_PAREN ")"
                SEMICOLON ";"
              WHITESPACE "\n    "
              R_CURLY "}"
        WHITESPACE "\n\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          IDENT_PAT
            NAME
              IDENT "result"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          BLOCK_EXPR
            LABEL
              LIFETIME
                LIFETIME_IDENT "'block"
              COLON ":"
            WHITESPACE " "
            STMT_LIST
              L_CURLY "{"
              WHITESPACE "\n        "
              EXPR_STMT
                IF_EXPR
                  IF_KW "if"
                  WHITESPACE " "
                  CALL_EXPR
                    PATH_EXPR
                      PATH
                        PATH_SEGMENT
                          NAME_REF
                            IDENT "foo"
                    ARG_LIST
                      L_PAREN "("
                      R_PAREN ")"
                  WHITESPACE " "
                  BLOCK_EXPR
                    STMT_LIST
                      L_CURLY "{"
                      WHITESPACE "\n            "
                      COMMENT "// comment"
                      WHITESPACE "\n            "
                      EXPR_STMT
                        BREAK_EXPR
                          BREAK_KW "break"
                          WHITESPACE " "
                          LIFETIME
                            LIFETIME_IDENT "'block"
                          WHITESPACE " "
                          LITERAL
                            INT_NUMBER "1"
                        SEMICOLON ";"
                      WHITESPACE "\n        "
                      R_CURLY "}"
              WHITESPACE "\n        "
              EXPR_STMT
                IF_EXPR
                  IF_KW "if"
                  WHITESPACE " "
                  CALL_EXPR
                    PATH_EXPR
                      PATH
                        PATH_SEGMENT
                          NAME_REF
                            IDENT "bar"
                    ARG_LIST
                      L_PAREN "("
                      R_PAREN ")"
                  WHITESPACE " "
                  BLOCK_EXPR
                    STMT_LIST
                      L_CURLY "{"
                      WHITESPACE "\n            "
                      COMMENT "/* comment */"
                      WHITESPACE "\n            "
                      EXPR_STMT
                        BREAK_EXPR
                          BREAK_KW "break"
                          WHITESPACE " "
                          LIFETIME
                            LIFETIME_IDENT "'block"
                          WHITESPACE " "
                          LITERAL
                            INT_NUMBER "2"
                        SEMICOLON ";"
                      WHITESPACE "\n        "
                      R_CURLY "}"
              WHITESPACE "\n        "
              LITERAL
                INT_NUMBER "3"
              WHITESPACE "\n    "
              R_CURLY "}"
          SEMICOLON ";"
        WHITESPACE "\n"
        R_CURLY "}"
  WHITESPACE "\n"