Alter all Webform's form with hook_form_BASE_FORM_ID_alter What is the base form_id for Webform's forms to use in hook_form_BASE_FORM_ID_alter()?

My website will have lots of Webforms and I'm looking the proper way to alter this huge amount of forms.
the base form is webform_client_form and hook look like 


  HOOK_form_webform_client_form_alter


or if using HOOK_form_alter we need statement as

if (strstr($form_id, 'webform_client_form_')) {
  //our code for all webforms
}