Three sets of changes: 1) Make sure that a user doesn't create a query with the same name as an existing query that the user owns. 2) When submitting a new named query, display the name of the query on the index page. 3) Allow optional arguments to indexargs_url by setting their value to None. This will show the argument only if there is a valid value. To match these, changed the template for all search templates so if an error is thrown due to #1 the user stays on the search page so they can fix the issue. Note that I did not add automated tests for these because I couldn't find existing tests for these code paths that I could adapt. I don't understand how the existing Action tests work and there is no doc for them.

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