code: def ci(pull_request):
      if pull_request == "false":
          print("Not a pull request; skipping")
          return
      base_branch = get_base_branch()
      file_paths = changed_files(base_branch)
      python_files = [fn for fn in file_paths if fn.endswith(".py")]
      c_files = [fn for fn in file_paths if fn.endswith((".c", ".h"))]
      fixed = []
      fixed.extend(normalize_whitespace(python_files))
      fixed.extend(normalize_c_whitespace(c_files))
      if not fixed:
          print("No whitespace issues found")
      else:
          count = len(fixed)
          print(
              f"Please fix the {n_files_str(count)} with whitespace issues"
          )
          print(
              "(on Unix you can run `make patchcheck` to make the fixes)"
          )
          sys.exit(1)
  
imports: import re
  import sys
  import shutil
  import os.path
  import subprocess
  import sysconfig
  import reindent
  import untabify
label_desc: Use image node_id 17 for calling a global function with example usage: ci(pull_request) without return types