Function is_sealable_payload_type 

pub fn is_sealable_payload_type(media_type: &str) -> bool

Whether media_type may be the type of a sealed payload: the grammar above, and not an envelope in an envelope (application/cose*), a stream that cannot be sealed until ADR 0006 P1 (application/cbor-seq, text/event-stream) or a multipart body.

use cratestack_core::is_sealable_payload_type;

assert!(is_sealable_payload_type("application/json"));
assert!(!is_sealable_payload_type("application/cose"));
assert!(!is_sealable_payload_type("text/event-stream"));
assert!(!is_sealable_payload_type("application/json; charset=utf-8"));