function Get-YeatsRotationLambdaArn {
<#
.SYNOPSIS
    Retrieves the environment-specific ARN for the Yeats rotation Lambda.

.PARAMETER EnvironmentTag
    [string] The 'alk:env' value for the Yeats rotation Lambda name.

.PARAMETER ProfileName
    [string] The AWS profile to use during search operation.

.PARAMETER Region
    [string] The AWS region to use during search operation.

.EXAMPLE
    Get-YeatsRotationLambdaArn -EnvironmentTag 'devshared' -ProfileName 'temp-dev'

arn:aws:lambda:us-east-1:327695573722:function:alk-devshared-yeats-process-rotation-event
#>

    [CmdletBinding()]
    [OutputType([string])]
    param (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [string] $EnvironmentTag,

        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [string] $ProfileName,

        [Parameter(Mandatory = $false)]
        [ValidateScript({$_ -in (Get-AWSRegion).region})]
        [string] $Region = 'us-east-1'
    )

    $logLead = Get-LogLeadName
    $result = $null

    Import-AWSModule

    # Build the Lambda name.  All of this is constant except for the environment designator.
    $lambdaName = "alk-${EnvironmentTag}-yeats-process-rotation-event"
    Write-Verbose "$logLead : Calculated Yeats rotation Lambda name as '$lambdaName'"

    try {

        $lambda = Get-LMFunctionConfiguration -FunctionName $lambdaName -ProfileName $ProfileName -Region $Region
        $result = $lambda.FunctionArn

        Write-Verbose "$logLead : Yeats rotation Lambda ARN = '$result'"

    } catch {

        Write-Warning "$logLead : Unable to find Yeats rotation Lambda named '$lambdaName' with provided input.`nError encountered was: '$PSItem'"
    }

    return $result
}