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diff --git a/Pwsh/Linq/UsingLinq-GroupBy-SelectorFunctions.ps1 b/Pwsh/Linq/UsingLinq-GroupBy-SelectorFunctions.ps1
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+using namespace System.Collections.Generic
+using namespace System.Linq
+using namespace System.Management.Automation
+
+$procs = Get-Process
+$groupProcs = [Enumerable]::GroupBy( $procs,
+    [Func[object, string]]{
+        param($p) return $p.Name })
+
+h1 'result of groupings'
+
+@(foreach($g in $groupProcs) {
+    @( $g | Measure-Object -Property VirtualMemorySize64, PrivateMemorySize64 -Sum -Average -Maximum )
+    | Add-Member -NotePropertyMembers @{ Name = $g.Key } -force -PassThru -ea ignore
+})
+    | Select -first 15
+    | ft -auto Name, Property, Count, Average, Sum, Maximum
+
+<#
+[3] Outputs
+
+Name               Property            Count          Average                Sum          Maximum
+----               --------            -----          -------                ---          -------
+Code               VirtualMemorySize64    26 3276366924563.69  85185540038656.00 3424346501120.00
+Code               PrivateMemorySize64    26     109425585.23      2845065216.00     622895104.00
+com.docker.service VirtualMemorySize64     1    5003096064.00      5003096064.00    5003096064.00
+com.docker.service PrivateMemorySize64     1      53522432.00        53522432.00      53522432.00
+
+#>
+
+
+$all_procs = Get-Process
+$select_parentPid =
+    [Func[object, string]]{
+        param($p) return $p.Parent.Id }
+
+$select_parentName =
+    [Func[object, string]]{
+        param($p) return $p.Parent.Name }
+
+$source = $all_procs
+$by_ParentPid = [Enumerable]::GroupBy(
+    <# source: #> $all_procs,
+    <# keySelector: #> $select_parentPid )
+
+function fmt.ProcName {
+    param(
+        [Parameter(ValueFromPipeline)]
+        [Diagnostics.Process]$InObj )
+    process {
+        "${fg:#ceceaa}{0}${fg:#555555} {1}${fg:clear}" -f @(
+            $InObj.Name, $InObj.Id
+        )
+    }
+}
+$by_ParentPid | %{
+    [pscustomobject]@{
+        Parent =
+            [string]::IsNullOrWhiteSpace( $_.Key ) ?
+                "`u{2400}" : $_.Key
+        Items = $_.GetEnumerator() | fmt.ProcName
+    }
+}
+
+<#
+[4] outputs....
+
+Parent Items
+------ -----
+␀      {AppleMobileDeviceService 5752, ApplicationFrameHost
+11540  {PowerToys.AlwaysOnTop 3168, PowerToys.ColorPickerUI 2188, PowerToys.CropAndLock 3328
+33524  {Code 1040, Code 15264, Code 25808, Code 26692…}
+28884  {Code 1236, rundll32 32480, steam 26536, WindowsTerm
+19064  {Code 11444, Code 13656, Code 14916, Code 18452…}
+1236   {Code 13580, Code 15940, Code 16208, Code 19064…}
+
+#>
+
+
+
+$names = Get-Process | % Name
+$groupedNames =
+    [Enumerable]::GroupBy( $names,
+        [Func[object,string]]{param($n) return $n})
+
+$groupedNames
+    | select -first 8
+    | Join-String -p { $_.key, @($_.GetEnumerator()).count } -sep "`n"
+
+<#
+[2] outputs:
+
+    Code 26
+    com.docker.service 1
+    CompPkgSrv 1
+    conhost 11
+    Discord 6
+    steam 1
+    svchost 97
+#>
+
+
+$groupedNames
+    | select -first 8
+    | Join-String -Property { $_.GetEnumerator() -join ', ' } -sep "`n"
+
+<#
+[1] outputs:
+
+    Code Code Code Code Code Code Code Code Code Code Code
+    com.docker.service
+    Discord Discord Discord Discord Discord Discord
+
+#>