code: def request_r(r, vi, sources, targets, dt_unit, ft_feature):
      # find the connector mapping to r, evaluate and store
      for connector in CreatorFunction.c_instances:
          if r in connector.output_rs:
              connector.map(vi, sources, targets, dt_unit, ft_feature)
  
file_path: deepgraph/deepgraph/connectors_and_selectors.py
imports: import inspect
  import warnings
  from collections import Counter
  import numpy
  from deepgraph._find_selected_indices import _find_selected_indices
  from deepgraph.utils import _flatten
label_desc: Use image node_id 3 for calling the Selector obj's underlying member method code with example usage: obj.request_r(r, vi, sources, targets, dt_unit, ft_feature) without return types