code: func (h *BlockHeader) BtcDecode(r io.Reader, pver uint32, enc MessageEncoding) error {
  	return readBlockHeader(r, pver, h)
  }
docs: // BtcDecode decodes r using the bitcoin protocol encoding into the receiver.
  // This is part of the Message interface implementation.
  // See Deserialize for decoding block headers stored to disk, such as in a
  // database, as opposed to decoding block headers from the wire.