Function heterogeneous_map 

pub fn heterogeneous_map<K, S>(
    d: &mut Decoder<'_>,
    state: S,
    decode_key: impl Fn(&mut Decoder<'_>) -> Result<K, Error>,
    decode_value: impl FnMut(&mut Decoder<'_>, &mut S, K) -> Result<(), Error>,
) -> Result<S, Error>

Decode any heterogeneous CBOR map, irrespective of whether they’re indefinite or definite.

A good choice for S is generally to pick a tuple of Option for each field item that needs decoding. For example:

let (address, value, datum, script) = decode_map(
    d,
    (None, None, MemoizedDatum::None, None),
    |d| d.u8(),
    |d, state, field| {
        match field {
            0 => state.0 = Some(decode_address(d.bytes()?),
            1 => state.1 = Some(d.decode()?),
            2 => state.2 = decode_datum()?,
            3 => state.3 = decode_reference_script()?,
            _ => return unexpected_field::<Output, _>(field),
        }
        Ok(())
    },
)?;