def remove_duplicate_bonds(bonds):
    """
    removes duplicates from [(at1, at2, 1.324), (at2, at1, 1.324)]
    """
    new_bonds = []
    pairs = []
    for k in bonds:
        pairs.append((k[0], k[1]))
        if (k[1], k[0]) in pairs:
            continue
        new_bonds.append(k)
    return new_bonds