original_string: private function convertOldDistributedList(&$yearMonths)
      {
          foreach ($yearMonths as $key => $value) {
              if (preg_match("/^[0-9]{4}_[0-9]{2}$/", $key)) {
                  unset($yearMonths[$key]);
  
                  $yearMonths[] = $key;
              }
          }
      }
code: private function convertOldDistributedList(&$yearMonths)
      {
          foreach ($yearMonths as $key => $value) {
              if (preg_match("/^[0-9]{4}_[0-9]{2}$/", $key)) {
                  unset($yearMonths[$key]);
  
                  $yearMonths[] = $key;
              }
          }
      }
code_tokens: private function convertOldDistributedList ( & $ yearMonths ) { foreach ( $ yearMonths as $ key => $ value ) { if ( preg_match ( "/^[0-9]{4}_[0-9]{2}$/" , $ key ) ) { unset ( $ yearMonths [ $ key ] ) ; $ yearMonths [ ] = $ key ; } } }
docstring: Before 2.12.0 Piwik stored this list as an array mapping year months to arrays of site IDs. If this is
  found in the DB, we convert the array to an array of year months to avoid errors and to make sure
  the correct tables are still purged.
docstring_tokens: Before 2 . 12 . 0 Piwik stored this list as an array mapping year months to arrays of site IDs . If this is found in the DB we convert the array to an array of year months to avoid errors and to make sure the correct tables are still purged .