<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _ensure_5args(func):
 """ Conditionally wrap function to ensure 5 input arguments Parameters func: callable with four or five positional arguments Returns ------- callable which possibly ignores 0 or 1 positional arguments """

    if func is None:
        return None

    self_arg = 1 if inspect.ismethod(func) else 0
    if len(inspect.getargspec(func)[0]) == 5 + self_arg:
        return func
    if len(inspect.getargspec(func)[0]) == 4 + self_arg:
        return lambda t, y, J, dfdt, fy=None: func(t, y, J, dfdt)
    else:
        raise ValueError("Incorrect numer of arguments")