WordPress SimplePie sanitization using KSES.
Sanitizes the incoming data, to ensure that it matches the type of data expected, using KSES.
(mixed) (Required) The data that needs to be sanitized.
(integer) (Required) The type of data that it's supposed to be.
(string) (Optional) The
xml:basevalue to use when converting relative URLs to absolute ones.
Default value: ''
(mixed) Sanitized data.