'Map the given FS path to a ZipPath, by looking at the ZipImporter\'s
"archive" attribute and using it as our ZipArchive root, then walking
down into the archive from there.
@return: a L{zippath.ZipPath} or L{zippath.ZipArchive} instance.'

def mapPath(self, fsPathString):

    za = ZipArchive(self.importer.archive)
    myPath = FilePath(self.importer.archive)
    itsPath = FilePath(fsPathString)
    if (myPath == itsPath):
        return za
    segs = itsPath.segmentsFrom(myPath)
    zp = za
    for seg in segs:
        zp = zp.child(seg)
    return zp
