def format_bytes(n):
    """Format bytes as text

    Copied from dask to avoid dependency.

    """
    if n > 1e15:
        return "%0.2f PB" % (n / 1e15)
    if n > 1e12:
        return "%0.2f TB" % (n / 1e12)
    if n > 1e9:
        return "%0.2f GB" % (n / 1e9)
    if n > 1e6:
        return "%0.2f MB" % (n / 1e6)
    if n > 1e3:
        return "%0.2f kB" % (n / 1000)
    return "%d B" % n