List all Media Targets
media_list_targets(name = NULL, identifier = NULL, data_source = NULL)
An array containing the following fields:
string, The name of the target.
string, A unique identifier for this target.
string, The source of viewership data for this target.
string optional. The name of the target.
string optional. A unique identifier for this target.
string optional. The source of viewership data for this target.