Function update_state_commitment 

pub fn update_state_commitment(
    prev_commitment: &[u8; 32],
    sapling_root: &[u8],
    orchard_root: &[u8],
    nullifier_root: &[u8],
    height: u32,
) -> [u8; 32]

Running state commitment chain (Blake2b-512, truncated to 32 bytes).

Chains sapling root, orchard root, nullifier root at each epoch boundary.