fix conversion

conversion.js

@@ -2,7 +2,14 @@ exports.name = 'masto_conversion';
 const fs = require('fs');
 const axios = require('axios');
 
+
 class Conversion {
+  constructor( ) {
+    this.fetched_times = 0;
+    this.max_fetchUsers = 5;
+    this.usersMemo = {};
+  }
+
   hello() {
     console.log('hello from conversion');
   }
@@ -172,9 +179,6 @@ class Conversion {
     });
   }
 
-  fetched_times = 0;
-  max_fetchUsers = 5;
-  usersMemo = {};
 
   /**
    * find user avatar url from its user homepage url.