RPCs that return detailed information about mempool entries (e.g. `getmempoolentry` and `getrawmempool(verbose=True)` include the fields `fee`, `modifiedfee`, `descendantfees`, and `ancestorfees` which were marked as "DEPRECATED" and replaced with a `fees` object field in #12240 (since v0.17).

We should remove these fields, but first, properly deprecate them using `-deprecatedrpc`.

#### Useful skills:

- basic understanding of Bitcoin Core RPC interface

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if (heightParam > 1000000000) {
        
        CBlockIndex* pindex = active_chain.FindEarliestAtLeast(heightParam - TIMESTAMP_WINDOW, 0);
        if (!pindex) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Could not find block with at least the specified timestamp.");
        }
        heightParam = pindex->nHeight;
    }
    unsigned int height = (unsigned int) heightParam;
    unsigned int chainHeight = (unsigned int) active_chain.Height();
    if (chainHeight < Params().PruneAfterHeight())
        throw JSONRPCError(RPC_MISC_ERROR, "Blockchain is too short for pruning.");
    else if (height > chainHeight)
        throw JSONRPCError(RPC_INVALID_PARAMETER, "Blockchain is shorter than the attempted prune height.");
    else if (height > chainHeight - MIN_BLOCKS_TO_KEEP) {
        LogPrint(BCLog::RPC, "Attempt to prune blocks close to the tip.  Retaining the minimum number of blocks.\n");
        height = chainHeight - MIN_BLOCKS_TO_KEEP;
    }
    PruneBlockFilesManual(active_chainstate, height);
    const CBlockIndex* block = active_chain.Tip();
    CHECK_NONFATAL(block);
    while (block->pprev && (block->pprev->nStatus & BLOCK_HAVE_DATA)) {
        block = block->pprev;
    }
    return uint64_t(block->nHeight);
},
    };
}
CoinStatsHashType ParseHashType(const std::string& hash_type_input)