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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _find_by_sha1(self, sha1):
 """ Return an |ImagePart| object belonging to this package or |None| if no matching image part is found. The image part is identified by the SHA1 hash digest of the image binary it contains. """

        for image_part in self:
            # ---skip unknown/unsupported image types, like SVG---
            if not hasattr(image_part, 'sha1'):
                continue
            if image_part.sha1 == sha1:
                return image_part
        return None