class_docstr: TSV data loader for files having a single input text and a label.
  
  Files must be in TSV format with 2 columns in this order:
  1. Input text.
  2. Numeric label.
  
  Exported examples have 2 output keys: "sentence" and "label".
code: def spec(self) -> lit_types.Spec:
      return {
          "sentence": lit_types.TextSegment(),
          "label": lit_types.CategoryLabel(vocab=self.LABELS),
      }
  
file_path: lit/lit_nlp/examples/is_eval/datasets.py
imports: from lit_nlp.api import dataset
  from lit_nlp.api import types
  import pandas
label_desc: Use image node_id 3 for calling the SingleInputClassificationFromTSV obj's underlying member method code with example usage: obj.spec() and returns: dict