'Initialize the copier.
:param read_all: Read function that blocks until the number of
requested bytes are read.
:param read_some: Read function that returns at least one byte, but may
not return the number of bytes requested.
:param outfile: File-like object to write output through.
:param delta_iter: Optional DeltaChainIterator to record deltas as we
read them.'

def __init__(self, read_all, read_some, outfile, delta_iter=None):

    super(PackStreamCopier, self).__init__(read_all, read_some=read_some)
    self.outfile = outfile
    self._delta_iter = delta_iter
