SOURCE_FILE
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "foo"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          IDENT_PAT
            NAME
              IDENT "_s"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          RECORD_EXPR
            PATH
              PATH_SEGMENT
                NAME_REF
                  IDENT "S"
            WHITESPACE " "
            RECORD_EXPR_FIELD_LIST
              L_CURLY "{"
              WHITESPACE " "
              DOT2 ".."
              WHITESPACE " "
              R_CURLY "}"
          SEMICOLON ";"
        WHITESPACE "\n"
        R_CURLY "}"
  WHITESPACE "\n"
