# Functions
New returns a new PieceDownloader.
# Variables
ErrBlockDuplicate is returned from PieceDownloader.GotBlock method when the received block is already present.
ErrBlockNotRequested is returned from PieceDownloader.GotBlock method when the received block is not requested yet.
# Structs
PieceDownloader downloads all blocks of a piece from a peer.
# Interfaces
Peer of a Torrent.