def verify_tersoff_2body_symmetry(tersoff_params):
    """
    Given a list of tersoff parameters, verify that they are such that
    the two-body parameters are symmetric.  What this means is that when
    we consider A-B B and B-A A, the two body parameters must be the same.
    This is necessary as LAMMPs will randomly isolate the two body
    interaction (A-B or B-A) and use the corresponding parameters.

    **Parameters**

        tersoff_params: *list,* :class:`squid.forcefields.tersoff.Tersoff`
            A list of Tersoff objects.

    **Returns**

        None
    """
    for i, ters_A in enumerate(tersoff_params):
        for j, ters_B in enumerate(tersoff_params):
            if i >= j:
                continue
            if all([ters_A.indices[0] == ters_B.indices[1], ters_A.indices[
                1] == ters_B.indices[0], ters_A.indices[1] == ters_A.
                indices[2], ters_B.indices[1] == ters_B.indices[2]]):
                assert all([ters_A.lambda1 == ters_B.lambda1, ters_A.
                    lambda2 == ters_B.lambda2, ters_A.A == ters_B.A, ters_A
                    .B == ters_B.B]
                    ), 'Error: 2-body symmetry requirements failed for %s' % str(
                    ters_A.indices[:2])
