How deal with missing data in nipype

@npann - we are hoping to address conditional logic in our next API

here are a few options we use at present:

  1. let branches fail and generate crashfiles.
  2. use a function node to guide things.
    • embed a workflow generator function inside a function node function
    • run the workflow or not depending on inputs.

Function Interfaces are quite powerful as they combine standard python control together with the ability to run workflows inside them.