def bytes_after(signature, length, bytestr):
    """
    Returns the bytes after the given signature

    :param bytes signature: the signature to find the bytes after
    :param int length: the length of the bytes to return
    :param bytes bytestr: the bytes to search in

    :returns: the bytes after the signature
    :rtype: bytes
    """
    start = bytestr.find(signature) + len(signature)
    return bytestr[start : start + length]