Hi there. We have a common pattern across flows where we have a

start_date

parameter that is not required. When the parameter is passed, we validate it and use it in the flow. When it's not passed, we use the flow's

scheduled_start_time

to derive the start date. This complicates the flow a little bit. I normally have to create a downstream task that takes the

Parameter

result and applies this logic. I was thinking that it would be nice to be able to pass a callable as the

default

argument of the

Parameter

class to provide a value if the parameter is missing. Similarly, it would be nice to have a

validator

callable that could be used to validate the parameter value. Is there another way to accomplish this? Thoughts?