Type hinting in doc.spans not working

[ghinch]

I am using doc.spans (ie. SpanGroups) to store some spans for reference later in my project. However, Pyright is throwing type errors on the values when I try to iterate through one of the SpanGroups, saying the type of the item is unknown. I can solve this using typing.cast, but it's not ideal to have to do this everywhere I want to use the spans. It seems like the type of the items in a span group should be known already.

Here is a basic example to illustrate the issue:

from typing import List
import spacy
from spacy.tokens import Doc, Span, SpanGroup
from spacy.language import Language

@Language.component("set_spans")
def set_spans(doc: Doc) -> Doc:
    # Itererate through the document and set a span for ever two tokens
    spans:List[Span] = []
    for i in range(0, len(doc), 2):
        start = i
        end = min(i + 2, len(doc))
        span = doc.char_span(start, end)
        if span:
            spans.append(span)
    doc.spans["pairs"] = SpanGroup(doc, spans=spans, name="pairs")
    return doc


def main():
    nlp = spacy.load("en_core_web_sm")
    nlp.add_pipe("set_spans", last=True)

    text = "This is a sample text for testing the span setting functionality."
    doc = nlp(text)

    for pair_span in doc.spans["pairs"]: # Type of "pair_span" is unknown
        print(pair_span)

Am I missing something?

[Mariihmp]

Use assert with isinstance check to inform the type checker about the object's type

pairs_group = doc.spans["pairs"]

assert isinstance(pairs_group, SpanGroup)`

  for pair_span in pairs_group: 
    print(pair_span)