human
I wrote the below code

    args = Mul.make_args(mul)
    fac_dum = dict([(fac, fac.atoms(Dummy)) for fac in args])
    fac_repr = dict([(fac, __kprint(fac)) for fac in args])
    all_dums = set().union(*fac_dum.values())
    mask = {}
    for d in all_dums:
        if d.assumptions0.get('below_fermi'):
            mask[d] = '0'
        elif d.assumptions0.get('above_fermi'):
            mask[d] = '1'
        else:
            mask[d] = '2'
    dum_repr = {d: __kprint(d) for d in all_dums}
    def _key(d):
        dumstruct = [fac for fac in fac_dum if (d in fac_dum[fac])]
        other_dums = set().union(*[fac_dum[fac] for fac in dumstruct])
        fac = dumstruct[(-1)]
        if (other_dums is fac_dum[fac]):
            other_dums = fac_dum[fac].copy()
        other_dums.remove(d)
        masked_facs = [fac_repr[fac] for fac in dumstruct]
        for d2 in other_dums:
            masked_facs = [fac.replace(dum_repr[d2], mask[d2]) for fac in masked_facs]
        all_masked = [fac.replace(dum_repr[d], mask[d]) for fac in masked_facs]
        masked_facs = dict(list(zip(dumstruct, masked_facs)))
        if has_dups(all_masked):
            all_masked.sort()
            return (mask[d], tuple(all_masked))
        keydict = dict(list(zip(dumstruct, all_masked)))
        dumstruct.sort(key=(lambda x: keydict[x]))
        all_masked.sort()
        pos_val = []
        for fac in dumstruct:
            if isinstance(fac, AntiSymmetricTensor):
                if (d in fac.upper):
                    pos_val.append('u')
                if (d in fac.lower):
                    pos_val.append('l')
            elif isinstance(fac, Creator):
                pos_val.append('u')
            elif isinstance(fac, Annihilator):
                pos_val.append('l')
            elif isinstance(fac, NO):
                ops = [op for op in fac if op.has(d)]
                for op in ops:
                    if isinstance(op, Creator):
                        pos_val.append('u')
                    else:
                        pos_val.append('l')
    ...

What's a good function header?
assistant
#Here's a good function header.

def _get_ordered_dummies(mul, verbose=False):