dist/flow.js
function () {
      var num = 0;
      var should = true;
      var simultaneousUploads = this.opts.simultaneousUploads;
      each(this.files, function (file) {
        each(file.chunks, function(chunk) {
          if (chunk.status() === 'uploading') {
            num++;
            if (num >= simultaneousUploads) {
              should = false;
              return false;
            }
          }
        });
      });
      // if should is true then return uploading chunks's length
      return should && num;
    }
function () {
      var num = 0;
      var should = true;
      var simultaneousUploads = this.opts.simultaneousUploads;
      each(this.files, function (file) {
        each(file.chunks, function(chunk) {
          if (chunk.status() === 'uploading') {
            num++;
            if (num >= simultaneousUploads) {
              should = false;
              return false;
            }
          }
        });
      });
      // if should is true then return uploading chunks's length
      return should && num;
    }
should upload next chunk
@function
@returns {boolean|number}