Hi folks. I’m curious... in the Metaflow python tutorials, I see things like this:

genre = Parameter(
    "genre",
    help="Filter movies for a particular genre.",
    default="Sci-Fi"
)

And then later:

if self.genre.lower() not in genres.lower()

Pylance quite reasonably complains about this:

Cannot access member "lower" for type "Parameter"
  Member "lower" is unknown Pylance(reportGeneralTypeIssues)

And yet the code runs just fine. I’ve hunted around and I’m unable to find the magic that allows calling

lower()

(a

string

method) on

genre

(a

Parameter

of type string). Can anyone help me to understand what’s going on here?

This may be what you are looking for: https://github.com/Netflix/metaflow/blob/master/metaflow/flowspec.py#L127