code: def custom_agg_handler(agg):
      if agg == "gmean":
          return stats.gmean
      if agg == "str_joiner":
          return str_joiner
      return agg
  
imports: import pandas
  from scipy import stats
  import dtale.global_state
  import dtale.pandas_util
  from dtale.query import run_query
  from dtale.utils import make_list
label_desc: Use image node_id 3 for calling a global function with example usage: custom_agg_handler(agg) and returns: agg, stats, str_joiner