Some default argument values are dict (which are mutable), a Python anti-pattern

[agzimmerman]

https://docs.python-guide.org/writing/gotchas/#mutable-default-arguments

For the most part I did an okay job of using None as the default argument value and then setting the mutable value in __init__; but there are many cases where I use a dict which is mutable and can lead to all sorts of unintended behavior. For example, the base class Simulation has a dict as the default value for solver_parameters.