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 " "
          TUPLE_STRUCT_PAT
            PATH
              PATH_SEGMENT
                NAME_REF
                  IDENT "S"
            L_PAREN "("
            R_PAREN ")"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          TUPLE_EXPR
            L_PAREN "("
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          TUPLE_STRUCT_PAT
            PATH
              PATH_SEGMENT
                NAME_REF
                  IDENT "S"
            L_PAREN "("
            WILDCARD_PAT
              UNDERSCORE "_"
            R_PAREN ")"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          TUPLE_EXPR
            L_PAREN "("
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          TUPLE_STRUCT_PAT
            PATH
              PATH_SEGMENT
                NAME_REF
                  IDENT "S"
            L_PAREN "("
            WILDCARD_PAT
              UNDERSCORE "_"
            COMMA ","
            R_PAREN ")"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          TUPLE_EXPR
            L_PAREN "("
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          TUPLE_STRUCT_PAT
            PATH
              PATH_SEGMENT
                NAME_REF
                  IDENT "S"
            L_PAREN "("
            WILDCARD_PAT
              UNDERSCORE "_"
            COMMA ","
            WHITESPACE " "
            REST_PAT
              DOT2 ".."
            WHITESPACE " "
            COMMA ","
            WHITESPACE " "
            IDENT_PAT
              NAME
                IDENT "x"
            R_PAREN ")"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          TUPLE_EXPR
            L_PAREN "("
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          TUPLE_STRUCT_PAT
            PATH
              PATH_SEGMENT
                NAME_REF
                  IDENT "S"
            L_PAREN "("
            PIPE "|"
            WHITESPACE " "
            IDENT_PAT
              NAME
                IDENT "a"
            R_PAREN ")"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          TUPLE_EXPR
            L_PAREN "("
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n"
        R_CURLY "}"
  WHITESPACE "\n"