requested size for the test (in arbitrary, test-interpreted
    units.) 'memuse' is the number of bytes per unit for the test, or a good
    estimate of it. For example, a test that needs two byte buffers, of 4 GiB
    each, could be decorated with @bigmemtest(size=_4G, memuse=2).

    The 'size' argument is normally passed to the decorated test method as an
    extra argument. If 'dry_run' is true, the value passed to the test method
    may be less than the requested value. If 'dry_run' is false, it means the
    test doesn't support dummy runs when -M is not specified.
    c