Refactor single use function

Author: ocelotl

opentelemetry-api/src/opentelemetry/auto_instrument/auto_instrument.py

@@ -16,27 +16,22 @@
 
 from shutil import which
 from os import environ, execl
-from os.path import dirname, pathsep
+from os.path import dirname, join
 from sys import argv
 
 
-def _add_bootstrap_to_pythonpath(bootstrap_dir):
-    """
-    Add our bootstrap directory to the head of $PYTHONPATH to ensure
-    it is loaded before program code
-    """
-    python_path = environ.get('PYTHONPATH', '')
+def run() -> None:
 
-    if python_path:
-        new_path = '%s%s%s' % (
-            bootstrap_dir, pathsep, environ['PYTHONPATH'])
-        environ['PYTHONPATH'] = new_path
-    else:
-        environ['PYTHONPATH'] = bootstrap_dir
+    bootstrap_dir = dirname(__file__)
+    python_path = environ.get("PYTHONPATH", None)
 
+    # Add our bootstrap directory to the head of $PYTHONPATH to ensure
+    # it is loaded before program code
+    if python_path is not None:
+        environ["PYTHONPATH"] = join(bootstrap_dir, python_path)
+    else:
+        environ["PYTHONPATH"] = bootstrap_dir
 
-def run() -> None:
-    _add_bootstrap_to_pythonpath(dirname(__file__))
     python3 = which(argv[1])
     execl(python3, python3, *argv[2:])  # type: ignore