Demo that shows how to use a utility function inside a PS Module

DemoModule.psm1

#private function
function new-baseEncode ($pat) {
  $encoded = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes((":{0}" -f $pat)))
  Write-Output $encoded
}

#public function
function New-EncodedMessage ($name, $data) {
    $encoded = new-baseEncode $data

    Write-Output @{
        Name = $name
        EncodedMessage = $encoded
    }
}

#making the public function visible to module consumers
Export-ModuleMember New-EncodedMessage