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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 fill_region(compound, n_compounds, region, overlap=0.2, seed=12345, edge=0.2, fix_orientation=False, temp_file=None):
 """Fill a region of a box with a compound using packmol. Parameters compound : mb.Compound or list of mb.Compound Compound or list of compounds to be put in region. n_compounds : int or list of int Number of compounds to be put in region. region : mb.Box or list of mb.Box Region to be filled by compounds. overlap : float, units nm, default=0.2 Minimum separation between atoms of different molecules. seed : int, default=12345 Random seed to be passed to PACKMOL. edge : float, units nm, default=0.2 Buffer at the edge of the region to not place molecules. This is necessary in some systems because PACKMOL does not account for periodic boundary conditions in its optimization. fix_orientation : bool or list of bools Specify that compounds should not be rotated when filling the box, default=False. temp_file : str, default=None File name to write PACKMOL's raw output to. Returns ------- filled : mb.Compound If using mulitple regions and compounds, the nth value in each list are used in order. For example, if the third compound will be put in the third region using the third value in n_compounds. """

    _check_packmol(PACKMOL)

    if not isinstance(compound, (list, set)):
        compound = [compound]
    if not isinstance(n_compounds, (list, set)):
        n_compounds = [n_compounds]
    if not isinstance(fix_orientation, (list, set)):
        fix_orientation = [fix_orientation]*len(compound)

    if compound is not None and n_compounds is not None:
        if len(compound) != len(n_compounds):
            msg = ("`compound` and `n_compounds` must be of equal length.")
            raise ValueError(msg)
    if compound is not None:
        if len(compound) != len(fix_orientation):
            msg = ("`compound`, `n_compounds`, and `fix_orientation` must be of equal length.")
            raise ValueError(msg)

    # See if region is a single region or list
    if isinstance(region, Box):  # Cannot iterate over boxes
        region = [region]
    elif not any(isinstance(reg, (list, set, Box)) for reg in region):
        region = [region]
    region = [_validate_box(reg) for reg in region]

    # In angstroms for packmol.
    overlap *= 10

    # Build the input file and call packmol.
    filled_xyz = _new_xyz_file()

    # List to hold file handles for the temporary compounds
    compound_xyz_list = list()
    try:
        input_text = PACKMOL_HEADER.format(overlap, filled_xyz.name, seed)

        for comp, m_compounds, reg, rotate in zip(compound, n_compounds, region, fix_orientation):
            m_compounds = int(m_compounds)

            compound_xyz = _new_xyz_file()
            compound_xyz_list.append(compound_xyz)

            comp.save(compound_xyz.name, overwrite=True)
            reg_mins = reg.mins * 10
            reg_maxs = reg.maxs * 10
            reg_maxs -= edge * 10  # Apply edge buffer
            input_text += PACKMOL_BOX.format(compound_xyz.name, m_compounds,
                                             reg_mins[0], reg_mins[1],
                                             reg_mins[2], reg_maxs[0],
                                             reg_maxs[1], reg_maxs[2],
                                            PACKMOL_CONSTRAIN if rotate else "")

        _run_packmol(input_text, filled_xyz, temp_file)

        # Create the topology and update the coordinates.
        filled = Compound()
        filled = _create_topology(filled, compound, n_compounds)
        filled.update_coordinates(filled_xyz.name)
    finally:
        for file_handle in compound_xyz_list:
            file_handle.close()
            os.unlink(file_handle.name)
        filled_xyz.close()
        os.unlink(filled_xyz.name)
    return filled