human
Here's a good function header given the following:
I wrote the below code

    if (gen.is_real is False):
        raise TypeError(filldedent("\n                                                can't    solve    inequalities    with    absolute\n                                                values    containing    non-real    variables"))
    def _bottom_up_scan(expr):
        exprs = []
        if (expr.is_Add or expr.is_Mul):
            op = expr.func
            for arg in expr.args:
                _exprs = _bottom_up_scan(arg)
                if (not exprs):
                    exprs = _exprs
                else:
                    args = []
                    for (expr, conds) in exprs:
                        for (_expr, _conds) in _exprs:
                            args.append((op(expr, _expr), (conds + _conds)))
                    exprs = args
        elif expr.is_Pow:
            n = expr.exp
            if (not n.is_Integer):
                raise ValueError('Only    Integer    Powers    are    allowed    on    Abs.')
            _exprs = _bottom_up_scan(expr.base)
            for (expr, conds) in _exprs:
                exprs.append(((expr ** n), conds))
        elif isinstance(expr, Abs):
            _exprs = _bottom_up_scan(expr.args[0])
            for (expr, conds) in _exprs:
                exprs.append((expr, (conds + [Ge(expr, 0)])))
                exprs.append(((- expr), (conds + [Lt(expr, 0)])))
        else:
            exprs = [(expr, [])]
        return exprs
    exprs = _bottom_up_scan(expr)
    mapping = {'<': '>', '<=': '>='}
    inequalities = []
    for (expr, conds) in exprs:
        if (rel not in mapping.keys()):
            expr = Relational(expr, 0, rel)
        else:
            expr = Relational((- expr), 0, mapping[rel])
        inequalities.append(([expr] + conds))
    return reduce_rational_inequalities(inequalities, gen)

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

def reduce_abs_inequality(expr, rel, gen):