code: def find_marker_line(contents, marker):
      try:
          marker_position = contents.index(marker)
      except:
          error(
              f"failed to find {marker!r} comment before the 'notebook:' matrix configuration",
              0,
          )
  
      return contents.count("\n", 0, marker_position) + 1
  
file_path: stellargraph/scripts/ci/validate_ci_workflow.py
imports: import yaml
  import sys
  import glob
  import os
  from collections import Counter
label_desc: Use image node_id 2 for calling a global function with example usage: find_marker_line(contents, marker) and returns: unknown