ErrFutureBlock is returned when a block's timestamp is in the future according to the current node.

ErrInvalidNumber is returned if a block's number doesn't equal its parent's plus one.

ErrPrunedAncestor is returned when validating a block requires an ancestor that is known, but the state of which is not available.

ErrUnknownAncestor is returned when validating a block requires an ancestor that is unknown.

Broadcaster defines the interface to enqueue blocks to fetcher, find peer.

ChainContext defines a small collection of methods needed to access the local blockchain.

ChainHeaderReader defines a small collection of methods needed to access the local blockchain during header verification.

Engine is an algorithm agnostic consensus engine.

Handler should be implemented if the consensus needs to handle and send peer messages.

Istanbul is a consensus engine to avoid byzantine failure.

P2PServer defines the interface for a p2p.server to get the local node's enode and to add/remove for static/trusted peers.

Peer defines the interface for a p2p.peer.

PoW is a consensus engine based on proof-of-work.