def export_fileid_map(self, fileid_map):
"""Export a file id map to a fileid map.
:param fileid_map: File id map, mapping paths to file ids
:return: A Git blob object (or None if there are no entries)
"""
from dulwich.objects import Blob
b = Blob()
b.set_raw_chunks(serialize_fileid_map(fileid_map))
return b
