human
I wrote the below code

    a = Wild('a', exclude=[x])
    b = Wild('b', exclude=[x])
    expr = powsimp(expr, combine='exp')
    retdict = {}
    def _test_term(expr, x):
        '\n                                Test    if    ``expr``    fits    the    proper    form    for    undetermined    coefficients.\n                                '
        if expr.is_Add:
            return all((_test_term(i, x) for i in expr.args))
        elif expr.is_Mul:
            if expr.has(sin, cos):
                foundtrig = False
                for i in expr.args:
                    if i.has(sin, cos):
                        if foundtrig:
                            return False
                        else:
                            foundtrig = True
            return all((_test_term(i, x) for i in expr.args))
        elif expr.is_Function:
            if (expr.func in (sin, cos, exp)):
                if expr.args[0].match(((a * x) + b)):
                    return True
                else:
                    return False
            else:
                return False
        elif (expr.is_Pow and expr.base.is_Symbol and expr.exp.is_Integer and (expr.exp >= 0)):
            return True
        elif (expr.is_Pow and expr.base.is_number):
            if expr.exp.match(((a * x) + b)):
                return True
            else:
                return False
        elif (expr.is_Symbol or expr.is_number):
            return True
        else:
            return False
    def _get_trial_set(expr, x, exprs=set([])):
        '\n                                Returns    a    set    of    trial    terms    for    undetermined    coefficients.\n\n                                The    idea    behind    undetermined    coefficients    is    that    the    terms    expression\n                                repeat    themselves    after    a    finite    number    of    derivatives,    except    for    the\n                                coefficients    (they    are    linearly    dependent).        So    if    we    collect    these,\n   ...

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

def _undetermined_coefficients_match(expr, x):