Dependency Sorting, first of kind

Let's say that we have a document type like this:

<a name="foo"/>
<a name="bar" depends-on="foo"/>
<a name="baz" depends-on="foo"/>
<a name="jaz" depends-on="foo bar"/>
<a name="spaz"/>
<a name="maz" depends-on="spaz bar"/>

You can see that some elements depen on other elements as functions
might depend on other functions in a programming language or classes
upon superclasses in an object oriented language. I've listed them in
dependence order above (all dependents are listed after their dependees)
but the goal is actually to be able to do that sort. I want to take
randomly sorted elements and print them in their sorted order.

I cannot think of a reasonably easy way to do that. Is there one?

 Paul Prescod


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