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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 _atoms(atoms_string):
 """Parse the atom string. Args: atoms_string (str):
 The atoms to plot, in the form ``"C.1.2.3,"``. Returns: dict: The atomic indices over which to sum the DOS. Formatted as:: {Element: [atom_indices]}. Indices are zero indexed for each atomic species. If an element symbol is included with an empty list, then all sites for that species are considered. """

    atoms = {}
    for split in atoms_string.split(','):
        sites = split.split('.')
        el = sites.pop(0)
        sites = list(map(int, sites))
        atoms[el] = np.array(sites) - 1
    return atoms