Hello, i have question about nChainWork:
The block index database gets loaded into memory when the node starts, in src/main.cpp LoadBlockIndexDB function,
the code "pindex->nChainWork = (pindex->pprev ? pindex->pprev->nChainWork : 0) + GetBlockProof(*pindex);", why do this?

nChainWork noted:"Total amount of work (expected number of hashes) in the chain up to and including this block".
here:https://en.bitcoin.it/wiki/Bitcoin_Core_0.11_(ch_6):_The_Blockchain

Thank you.