! オブジェクトの属性データを取得する

オブジェクト（例えばデータフレーム）の項目名などの属性を取り出したい場合に使う。

  > attributes(d)

出力は、

   $names
 [1] "seqNumber"            "docID"                "edinetCode"           "secCode"             
 [5] "JCN"                  "filerName"            "fundCode"             "ordinanceCode"       
 [9] "formCode"             "docTypeCode"          "periodStart"          "periodEnd"           
 [13] "submitDateTime"       "docDescription"       "issuerEdinetCode"     "subjectEdinetCode"   
 [17] "subsidiaryEdinetCode" "currentReportReason"  "parentDocID"          "opeDateTime"         
 [21] "withdrawalStatus"     "docInfoEditStatus"    "disclosureStatus"     "xbrlFlag"            
 [25] "pdfFlag"              "attachDocFlag"        "englishDocFlag"       "processDateTime"     

  $row.names
 [1]  1  2  3  4  5  6  7  8  9 10

  $class
 [1] "tbl_df"     "tbl"        "data.frame"