public/release/Export-PSTSReleaseDefinition.ps1

function Export-PSTSReleaseDefinition
{
    param(
      [Parameter(Mandatory = $true, ValueFromPipelineByPropertyName = $true)][string] $project,
      [Parameter(Mandatory = $true, ValueFromPipelineByPropertyName = $true)][int] $releaseId,
      [Parameter(Mandatory = $true, ValueFromPipelineByPropertyName = $true)][string] $outFile
    )

    process {

        $content = Get-PSTSReleaseDefinition `
        -project $project `
        -releaseId $releaseId

        $($content | ConvertTo-json) | Out-File -FilePath $outFile
    }
}