The del_threshold is hardcoded in step function type custom

[SarahAlidoost]

As can be seen here, first threshold is calculated and then it is used in link_deletion. Therefore, users can no longer modify the threshold or switch to a different del_method, such as probability.

[vmgaribay]

It is a custom step, so users shouldn't be using it casually; that is, I believe, the purpose of having different steps such as "default". Creating a new method for "equalize" or an assert for the method used in the step or an if case is a good idea, but it is also a complete non-priority.

[vmgaribay]

I have renamed "custom" as "ptm" and added an acceptable threshold value "balance" which triggers a conditional case in the "ptm" step. It is part of the sensitivity analysis pull request.