Some .Net Methods and external programs output their exit code and other output to stdout.
You can either add the void keyword to the arraylist “Add” command or pipe it to Out-Null
$MyList = [System.Collections.ArrayList]@()
1..10 | % { $MyList.Add($_) } # outputs 0 to 9
1..10 | % { [void]$MyList.Add($_) } # no output
1..10 | % { $MyList.Add($_) | Out-Null } # no output
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