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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 _symm_current(C):
 """To get rid of NaNs produced by _scalar2array, symmetrize operators where C_ijkl = C_klij"""

    nans = np.isnan(C)
    C[nans] = np.einsum('klij', C)[nans]
    return C