Function import_proof_data 

pub fn import_proof_data(
    segments: &[Segment],
) -> (impl IntoIterator<Item = (CdMerkleProof, Vec<Hash>)>, SegmentTreeRoot)

Prepare import proof data for a set of segments. This function splits the segment into PROVEN_PER_SEGMENT pages and for each page returns a page prefix proof along with the vector of PROVEN_PER_SEGMENT hashes that form the page.