gm_attachment: Retrieve an attachment to a message
Description
This is a low level function to retrieve an attachment to a message by id of the attachment
and message. Most users are better off using gm_save_attachments() to
automatically save all the attachments in a given message.
Usage
gm_attachment(id, message_id, user_id = "me")
Arguments
id
id of the attachment
message_id
id of the parent message
user_id
gmail user_id to access, special value of 'me' indicates the authenticated user.