def METHOD_NAME(self, pos, whence=0):
    """Seek to specified position into the chunk.
    Default position is 0 (start of chunk).
    If the file is not seekable, this will result in an error.
    """
    if self.closed:
        raise ValueError("I/O operation on closed file")
    if not self.seekable:
        raise OSError("cannot seek")
    if whence == 1:
        pos = pos + self.size_read
    elif whence == 2:
        pos = pos + self.chunksize
    if pos < 0 or pos > self.chunksize:
        raise RuntimeError
    self.file.METHOD_NAME(self.offset + pos, 0)
    self.size_read = pos