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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 create_saturated_interstitial_structure( interstitial_def, dist_tol=0.1):
 """ this takes a Interstitial defect object and generates the sublattice for it based on the structure's space group. Useful for understanding multiplicity of an interstitial defect in thermodynamic analysis. NOTE: if large relaxation happens to interstitial or defect involves a complex then there maybe additional degrees of freedom that need to be considered for the multiplicity. Args: dist_tol: changing distance tolerance of saturated structure, allowing for possibly overlapping sites but ensuring space group is maintained Returns: Structure object decorated with interstitial site equivalents """

    sga = SpacegroupAnalyzer( interstitial_def.bulk_structure.copy())
    sg_ops = sga.get_symmetry_operations( cartesian=True)

    # copy bulk structure to make saturated interstitial structure out of
    # artificially lower distance_tolerance to allow for distinct interstitials
    # with lower symmetry to be replicated - This is OK because one would never
    # actually use this structure for a practical calcualtion...
    saturated_defect_struct = interstitial_def.bulk_structure.copy()
    saturated_defect_struct.DISTANCE_TOLERANCE = dist_tol

    for sgo in sg_ops:
        new_interstit_coords = sgo.operate( interstitial_def.site.coords[:])
        poss_new_site = PeriodicSite(
                interstitial_def.site.specie,
                new_interstit_coords,
                saturated_defect_struct.lattice,
                to_unit_cell=True,
                coords_are_cartesian=True)
        try:
            #will raise value error if site already exists in structure
            saturated_defect_struct.append(
                        poss_new_site.specie, poss_new_site.coords,
                        coords_are_cartesian=True, validate_proximity=True)
        except ValueError:
            pass

    # do final space group analysis to make sure symmetry not lowered by saturating defect structure
    saturated_sga = SpacegroupAnalyzer( saturated_defect_struct)
    if saturated_sga.get_space_group_number() != sga.get_space_group_number():
        raise ValueError("Warning! Interstitial sublattice generation "
                         "has changed space group symmetry. I recommend "
                         "reducing dist_tol and trying again...")

    return saturated_defect_struct