def _typecheck1 (object, spec):
    if type(spec) is type:
        return type(object) is spec
    elif type(spec) is list:
        for s in spec:
            if _typecheck1(object, s): return True
        return False
    elif type(spec) is tuple:
        if spec[0] == tuple:
            if type(object) is not tuple or len(object) != len(spec)-1:
                return False
            for o, s in zip(object, spec[1:]):
                if not _typecheck1(o, s): return False
            return True
        elif spec[0] == list:
            if type(object) is not list or\
                (len(spec) >= 3 and len(object) < spec[2]) or\
                (len(spec) >= 4 and len(object) > spec[3]):
                return False
            for o in object:
                if not _typecheck1(o, spec[1]): return False
            return True
        elif spec[0] == dict:
            if type(object) is not dict: return False
            for (k, v) in object.items():
                if not _typecheck1(k, spec[1]): return False
                if not _typecheck1(v, spec[2]): return False
            return True
        else:
            return False
    else:
        return False

def _formatSpec (spec):
    if type(spec) is type:
        return str(spec)
    elif type(spec) is list:
        m = ""
        for s in spec:
            if m != "": m += " or "
            m += _formatSpec(s)
        return m
    elif type(spec) is tuple:
        if spec[0] == tuple:
            m = ""
            for s in spec[1:]:
                if m != "": m += ", "
                m += _formatSpec(s)
            return "tuple (" + m + ")"
        elif spec[0] == list:
            m = "list"
            if len(spec) >= 3:
                m += " " + str(spec[2]) + ".."
                if len(spec) >= 4:
                    m += str(spec[3])
                else:
                    m += "*"
            return m + " [" + _formatSpec(spec[1]) + "]"
        elif spec[0] == dict:
            return "dictionary {" + _formatSpec(spec[1]) + " : " +\
                _formatSpec(spec[2]) + "}"
        else:
            return "?"
    else:
        return "?"

def _typecheck (argNum, object, spec):
    if __debug__:
        if not _typecheck1(object, spec):
            if argNum > 0:
                m = "argument " + str(argNum) + ": "
            else:
                m = ""
            raise TypeError, m + "expecting " + _formatSpec(spec)