import select


def read_ready(*read_fds, timeout=None):
    """Returns a list of file descriptors that are ready to be read.

    Args:
        *read_fds (int): Integers that refer to the file descriptors.
        timeout (float): A timeout before returning an empty list if no file
            descriptor is ready. None waits until at least one file descriptor
            is ready.
    """
    return [] if not read_fds else select.select(read_fds, [], [], timeout)[0]