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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 break_bond(self, ind1, ind2, tol=0.2):
 """ Returns two molecules based on breaking the bond between atoms at index ind1 and ind2. Args: ind1 (int):
 Index of first site. ind2 (int):
 Index of second site. tol (float):
 Relative tolerance to test. Basically, the code checks if the distance between the sites is less than (1 + tol) * typical bond distances. Defaults to 0.2, i.e., 20% longer. Returns: Two Molecule objects representing the two clusters formed from breaking the bond. """

        sites = self._sites
        clusters = [[sites[ind1]], [sites[ind2]]]

        sites = [site for i, site in enumerate(sites) if i not in (ind1, ind2)]

        def belongs_to_cluster(site, cluster):
            for test_site in cluster:
                if CovalentBond.is_bonded(site, test_site, tol=tol):
                    return True
            return False

        while len(sites) > 0:
            unmatched = []
            for site in sites:
                for cluster in clusters:
                    if belongs_to_cluster(site, cluster):
                        cluster.append(site)
                        break
                else:
                    unmatched.append(site)

            if len(unmatched) == len(sites):
                raise ValueError("Not all sites are matched!")
            sites = unmatched

        return (self.__class__.from_sites(cluster)
                for cluster in clusters)