Calling a Returned Value to Another Function

[valerydolce]

What should be the "some_env_var_name" in this case ?

When i test the code below, 

#! /usr/bin/python3

import os
import sys

def get_environment_variable_value(variable_name):
    var_name = os.environ[variable_name]
    if not var_name:
        return ""
    else:
        return var_name

def get_dirs_from_path():
    path_var = get_environment_variable_value(variable_name)
    directories = path_var.split(':')
    for entry in directories:
        print (entry)


get_environment_variable_value('PATH')
get_dirs_from_path()

it prints the following output:

Output:
psimo@itserver6:~/it117/hw/hw6$ ./hw66.py
Traceback (most recent call last):
  File "./hw66.py", line 22, in <module>
    get_dirs_from_path()
  File "./hw66.py", line 15, in get_dirs_from_path
    path_var = get_environment_variable_value(variable_name)
NameError: name 'variable_name' is not defined
psimo@itserver6:~/it117/hw/hw6$