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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 _scalar2array(d):
 """Convert a dictionary with scalar elements and string indices '_1234' to a dictionary of arrays. Unspecified entries are np.nan."""

    da = {}
    for k, v in d.items():
        if '_' not in k:
            da[k] = v
        else:
            name = ''.join(k.split('_')[:-1])
            ind = k.split('_')[-1]
            dim = len(ind)
            if name not in da:
                shape = tuple(3 for i in range(dim))
                da[name] = np.empty(shape, dtype=complex)
                da[name][:] = np.nan
            da[name][tuple(int(i) - 1 for i in ind)] = v
    return da