Reverse TextIndent (Outdent) for FlowDocument

WPF FlowDocuments are extremely useful and format very nicely, so long as you are writing plain text.  The tag kindly provides a TextIndent attribute, to indent the first line of the paragraph.  But, what about formatting for nested code?

Margin doesn't look kindly upon inserting negative values, but TextIndent gladly accepts them.  Using a combination of a negative TextIndent and a matching, positive left margin, the Paragraph is coaxed into outdenting the first line.  This visually appears that the first line is even with the other paragraphs, and the following lines are indented.

<paragraph 
            margin="25,0,0,0"
            textindent="-25"
            FontFamily="Courier">
    First Line
    Second line
    Third Line
</paragraph>

Produces the following:

First Line
    Second Line
    Third Line

Admittedly, this works well for the first indent, but any further indentations must be handled with a bit of creativity. I will leave you to decide how to best handle that situation.