TODO: triage
TODO: removed a task

bind_with_defaults() takes about 100us, which is less than the execution time of most kernels
and will be hidden by asynchronous execution.
(even if it doesn't, it will be clearly seen during profiling).
core/transformation: removed an obsolete comment
Using a special object as the container of index variable names instead of just a list.
pureparallel: fixed a reference to a class
test/computations/pureparallel: removed unused imports