this:</p>

<pre><code>function Start-MigrationOperation
{
    [CmdletBinding()]
    param(
        [Parameter(Mandatory=$true)]
        [Rivet.Migration]
        # The migration the operation is part of.
        $Migration,

        [Parameter(Mandatory=$true)]
        [Rivet.Operation]
        # The operation which is about to be applied.
        $Operation
    )

    Set-StrictMode -Version 'Latest'

    if( $Operation -is [Rivet.Operations.ConstraintOperation] )
    {
        switch( $Operation.Constrain