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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 fei_metadata(self):
 """Return FEI metadata from SFEG or HELIOS tags as dict."""

        if not self.is_fei:
            return None
        tags = self.pages[0].tags
        if 'FEI_SFEG' in tags:
            return tags['FEI_SFEG'].value
        if 'FEI_HELIOS' in tags:
            return tags['FEI_HELIOS'].value
        return None