Add a key transformer

package-lock.json

@@ -415,7 +415,7 @@
       "integrity": "sha512-4OcjOJQByI0YDU5COYw9HAqjo8/MOLLmT9EKyMCXUzgvh30vS1SlMK+Ho84IH5exN44cSnrYecw/7Zpu2m4lkA=="
     },
     "csv-readable": {
-      "version": "git+https://gitlab+deploy-token-4:Htg4YFbNZ28_dqSfrtxp@source.dodis.ch/histhub/csvreadable.git#e54c9d73164fb30f2a4506c9f69df96137184296",
+      "version": "git+https://gitlab+deploy-token-4:Htg4YFbNZ28_dqSfrtxp@source.dodis.ch/histhub/csvreadable.git#6bc5c6146bbcaae995b31c133f7e931bf165690e",
       "from": "git+https://gitlab+deploy-token-4:Htg4YFbNZ28_dqSfrtxp@source.dodis.ch/histhub/csvreadable.git",
       "requires": {
         "@types/node": "^9.6.6",

src/index.ts

@@ -16,6 +16,10 @@ class Fundmuenzen extends CsvReadable {
     return callback(null, record);
   }
 
+  public transformDataKey(records: any) {
+    return `fundmuenzen${records[3].toString()}`;
+  }
+
   public transformData(records: any): InterfaceGeolinker | null {
     if (this.header) {
       return null;