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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 from_iso(cls, iso):
 """Retrieve the first datacenter id associated to an ISO."""

        result = cls.list({'sort_by': 'id ASC'})
        dc_isos = {}
        for dc in result:
            if dc['iso'] not in dc_isos:
                dc_isos[dc['iso']] = dc['id']

        return dc_isos.get(iso)