How does BEGIN PROCESS END Blocks work in the pipeline

Pipeline.ps1

function A
{
    [CmdletBinding()]
    Param
    (
        [parameter(ValueFromPipeline=$true)]
        $MyParam
    )

    Begin
    {
        $currentfunction = (Get-Variable -name myinvocation -scope 0 -ValueOnly).mycommand
        Write-Verbose -Message "[Function $Currentfunction] BEGIN Block"

    }
    Process
    {
        Write-Verbose -Message "[Function $Currentfunction] PROCESS Block"
        Write-Output -InputObject $MyParam
    }
    End
    {
     Write-Verbose -Message "[Function $Currentfunction] END Block"
    }
}

function B
{
    [CmdletBinding()]
    Param
    (
        [parameter(ValueFromPipeline=$true)]
        $MyParam
    )

    Begin
    {
        $currentfunction = (Get-Variable -name myinvocation -scope 0 -ValueOnly).mycommand
        Write-Verbose -Message "[Function $Currentfunction] BEGIN Block"

    }
    Process
    {
        Write-Verbose -Message "[Function $Currentfunction] PROCESS Block"
        Write-Output -InputObject $MyParam
    }
    End
    {
     Write-Verbose -Message "[Function $Currentfunction] END Block"
    }
}

function C
{
    [CmdletBinding()]
    Param
    (
        [parameter(ValueFromPipeline=$true)]
        $MyParam
    )

    Begin
    {
        $currentfunction = (Get-Variable -name myinvocation -scope 0 -ValueOnly).mycommand
        Write-Verbose -Message "[Function $Currentfunction] BEGIN Block"

    }
    Process
    {
        Write-Verbose -Message "[Function $Currentfunction] PROCESS Block"
        Write-Output -InputObject $MyParam
    }
    End
    {
     Write-Verbose -Message "[Function $Currentfunction] END Block"
    }
}


1..10 | A -Verbose | B -Verbose |C -Verbose

#OUTPUT
<#

1..10 | A -Verbose | B -Verbose |C -Verbose
VERBOSE: [Function A] BEGIN Block
VERBOSE: [Function B] BEGIN Block
VERBOSE: [Function C] BEGIN Block
VERBOSE: [Function A] PROCESS Block
VERBOSE: [Function B] PROCESS Block
VERBOSE: [Function C] PROCESS Block
1
VERBOSE: [Function A] PROCESS Block
VERBOSE: [Function B] PROCESS Block
VERBOSE: [Function C] PROCESS Block
2
VERBOSE: [Function A] PROCESS Block
VERBOSE: [Function B] PROCESS Block
VERBOSE: [Function C] PROCESS Block
3
VERBOSE: [Function A] PROCESS Block
VERBOSE: [Function B] PROCESS Block
VERBOSE: [Function C] PROCESS Block
4
VERBOSE: [Function A] PROCESS Block
VERBOSE: [Function B] PROCESS Block
VERBOSE: [Function C] PROCESS Block
5
VERBOSE: [Function A] PROCESS Block
VERBOSE: [Function B] PROCESS Block
VERBOSE: [Function C] PROCESS Block
6
VERBOSE: [Function A] PROCESS Block
VERBOSE: [Function B] PROCESS Block
VERBOSE: [Function C] PROCESS Block
7
VERBOSE: [Function A] PROCESS Block
VERBOSE: [Function B] PROCESS Block
VERBOSE: [Function C] PROCESS Block
8
VERBOSE: [Function A] PROCESS Block
VERBOSE: [Function B] PROCESS Block
VERBOSE: [Function C] PROCESS Block
9
VERBOSE: [Function A] PROCESS Block
VERBOSE: [Function B] PROCESS Block
VERBOSE: [Function C] PROCESS Block
10
VERBOSE: [Function A] END Block
VERBOSE: [Function B] END Block
VERBOSE: [Function C] END Block

#>