text: import DocToHeader from './DocToHeader.js';
  
  // Internal used
  var LoadHeader = function (fileID) {
      var userID = this.userID;
      let header = this.cacheHeaders[fileID];
      if (header && (header.userID === userID)) {
          return Promise.resolve(header);
      }
  
      // Can't find in cache headers, load from firestore    
      var self = this;
      return this.getFileQuery(userID, fileID, 'header').limit(1).get()
          .then(function (querySnapshot) {
              let header = undefined;
              if (querySnapshot.size > 0) {
                  var doc = querySnapshot.docs[0];
                  header = DocToHeader(doc);
                  self.cacheHeaders[fileID] = header; // Cache it
              }
              return Promise.resolve(header);
          });
  }
  
  export default LoadHeader;