code: func (f *Field) AbsorbPiece(piece *Piece, x, y int, angle Angle) {
  	piece.AbsorbInto(f, x, y, angle)
  	if f.flushable() {
  		f.flushCount = maxFlushCount
  	}
  }
docs: // AbsorbPiece absorbs the piece at (x, y) with the given angle into the field.