allows for custom determination of condition to assign. Custom function * must be located in `custom.py`, * must be named `custom_get_condition` * must accept a single argument (the current `mode` will be passed to it) * and must return a tuple `(condition, counterbalance)` integers, e.g. `(0,0)` for condition 0 and counterbalance 0.
allows for custom determination of condition to assign. Custom function
* must be located in `custom.py`,
* must be named `custom_get_condition`
* must accept a single argument (the current `mode` will be passed to it)
* and must return a tuple `(condition, counterbalance)` integers, e.g. `(0,0)` for condition 0 and
counterbalance 0.

NYUCCL/psiTurk,NYUCCL/psiTurk,NYUCCL/psiTurk