SOURCE_FILE
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "main"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          BOX_PAT
            BOX_KW "box"
            WHITESPACE " "
            IDENT_PAT
              NAME
                IDENT "i"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          TUPLE_EXPR
            L_PAREN "("
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          BOX_PAT
            BOX_KW "box"
            WHITESPACE " "
            RECORD_PAT
              PATH
                PATH_SEGMENT
                  NAME_REF
                    IDENT "Outer"
              WHITESPACE " "
              RECORD_PAT_FIELD_LIST
                L_CURLY "{"
                WHITESPACE " "
                RECORD_PAT_FIELD
                  BOX_PAT
                    BOX_KW "box"
                    WHITESPACE " "
                    IDENT_PAT
                      NAME
                        IDENT "i"
                COMMA ","
                WHITESPACE " "
                RECORD_PAT_FIELD
                  NAME_REF
                    IDENT "j"
                  COLON ":"
                  WHITESPACE " "
                  BOX_PAT
                    BOX_KW "box"
                    WHITESPACE " "
                    TUPLE_STRUCT_PAT
                      PATH
                        PATH_SEGMENT
                          NAME_REF
                            IDENT "Inner"
                      L_PAREN "("
                      BOX_PAT
                        BOX_KW "box"
                        WHITESPACE " "
                        REF_PAT
                          AMP "&"
                          IDENT_PAT
                            NAME
                              IDENT "x"
                      R_PAREN ")"
                WHITESPACE " "
                R_CURLY "}"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          TUPLE_EXPR
            L_PAREN "("
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          BOX_PAT
            BOX_KW "box"
            WHITESPACE " "
            IDENT_PAT
              REF_KW "ref"
              WHITESPACE " "
              MUT_KW "mut"
              WHITESPACE " "
              NAME
                IDENT "i"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          TUPLE_EXPR
            L_PAREN "("
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n"
        R_CURLY "}"
  WHITESPACE "\n"
