PowerShell Unix Epoch Conversions

ConvertFrom-Epoch.ps1

function ConvertFrom-Epoch {
    [CmdletBinding()]
    [OutputType([datetime])]
    param (
        [Parameter(ValueFromPipeline, Mandatory)]
        [ValidateNotNullOrEmpty()]
        [long]
        $Epoch,
        [switch]
        $FromMilliseconds,
        [switch]
        $AsLocalTime
    )
    process {
        if ($FromMilliseconds.IsPresent) {
            $offset =  [System.DateTimeOffset]::FromUnixTimeMilliseconds($Epoch)
        }
        else {
            $offset = [System.DateTimeOffset]::FromUnixTimeSeconds($Epoch)
        }
        if ($AsLocalTime.IsPresent) {
            return $offset.UtcDateTime.ToLocalTime()    
        }
        $offset.UtcDateTime
    }
}

ConvertTo-Epoch.ps1

function ConvertTo-Epoch {
    [CmdletBinding()]
    [OutputType([long])]
    param (
        [Parameter(ValueFromPipeline, Mandatory)]
        [ValidateNotNullOrEmpty()]
        [datetime]
        $Date,
        [switch]
        $AsMilliseconds
    )
    process {
        $offset = [System.DateTimeOffset]::New($Date.ToUniversalTime())
        if ($AsMilliseconds.IsPresent) {
            return $offset.ToUnixTimeMilliseconds()   
        }
        $offset.ToUnixTimeSeconds()
    }
}