code: def _get_groupby(f):
      if isinstance(f, GroupByTransformFeature):
          return f.groupby.unique_name()
      else:
          return ""
  
file_path: featuretools/featuretools/computational_backends/feature_set.py
imports: import itertools
  import logging
  from collections import defaultdict
  from featuretools.entityset.relationship import RelationshipPath
  from featuretools.feature_base import AggregationFeature, FeatureOutputSlice, GroupByTransformFeature, TransformFeature
  from featuretools.utils import Trie
label_desc: Use image node_id 3 for calling a global function with example usage: _get_groupby(f) and returns: f, str