Use tuples for default arguments in DAP

Use tuples for default arguments in DAP

My co-worker Kévin taught me that using a mutable object as a default
argument in Python is somewhat dangerous, because the object is
created a single time (when the function is defined), and so if it is
mutated in the body of the function, the changes will stick around.

This patch changes the cases like this in DAP to use () rather than []
as the default.  This patch is merely preventative, as no bugs like
this are in the code.