Code Snippet formatting literal

[danieljroot]

I would like to create a code snippet for a property that automatically
names the underlying field with standard naming convention:
typing propn string MyProp

would expand to:

private string myProp;
public string MyProp
{
....
}

(as opposed to the standard property snippet, which requires you to
enter the name twice.)
Is there any way to format the literal string in my snippet? Other
snippet tools let you do something similar by using special escape
sequences, something like this:

private $Type$ $l:PropertyName $;
public $Type$ $u:PropertyName $
{
....
}

I noticed there is a "Function" element, but these seem to be hard
coded functions and pretty limited.