def set_signature(library, function_name, argtypes, restype, errcheck):
    """Set the signature of single function in a library.

    :param library: ctypes wrapped library.
    :type library: ctypes.WinDLL or ctypes.CDLL
    :param function_name: name of the function as appears in the header file.
    :type function_name: str
    :param argtypes: a tuple of ctypes types to specify the argument types that the function accepts.
    :param restype: A ctypes type to specify the result type of the foreign function.
                    Use None for void, a function not returning anything.
    :param errcheck: a callabe

    :raises: AttributeError
    """

    func = getattr(library, function_name)
    func.argtypes = argtypes
    if restype is not None:
        func.restype = restype
    if errcheck is not None:
        func.errcheck = errcheck