def _find_by_sha1(self, sha1):
        for image_part in self:
            if image_part.sha1 == sha1:
                return image_part
        return None
Return an |ImagePart| object belonging to this package or |None| if
dataset/ETHPy150Open scanny/python-pptx/pptx/package.py/_ImageParts._find_by_sha1