addTensorDepthsOption = (v, k) => {
        if (typeof k !== 'string' || typeof v !== 'number') {
          throw new Error(
              '"tensorDepths" option must be an object of' +
              ' type Object<string, number>');
        }
        result[k] = v;
      }
@param {!Object} params An ExportParameters parameter list
    which contains format-specific prefix options.
@return {!ee.api.TfRecordImageExportOptions}
@private