def findBlock(pieceIndex, offset, length)
      leftOffset = @pieceSize*pieceIndex + offset
      rightOffset = leftOffset + length-1

      findPart(leftOffset, rightOffset)
    end
def findBlock(pieceIndex, offset, length)
      leftOffset = @pieceSize*pieceIndex + offset
      rightOffset = leftOffset + length-1

      findPart(leftOffset, rightOffset)
    end
Return a list of FileRegion objects. The FileRegion offsets specify
 in order which regions of files the piece covers.