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    # Avoid thrashing this procedure
    # Note Perl does not support usleep
...
    #    'select undef, undef, undef, 0.1;'
    # to sleep for (at least) 0.1 seconds
    sleep(100);

use OpenGL qw(:all);    # Use the OpenGL module
use strict;             # Use strict typechecking
use Time::HiRes qw[ usleep ];

    # to sleep for (at least) 0.1 seconds
    usleep(100);