import os
import subprocess

# Set an environment variable in the parent process
os.environ["PARENT_VARIABLE"] = "12345s"

# Spawn a subprocess and modify the environment variable
subprocess.run(
    [
        "python",
        "-c",
        "import os; print('b', os.environ['PARENT_VARIABLE']); os.environ['PARENT_VARIABLE'] = 'modified_value'; print('c', os.environ['PARENT_VARIABLE'])",
    ]
)

# Check if the modification in the subprocess affected the parent process
print("a", os.environ["PARENT_VARIABLE"])  # This will print 'parent_value', not 'modified_value'