Still confused about how passing arguments works

[RedSkeleton007]

I have a simple user input program:

#!/usr/bin/python
#QuickTest.py

def getLocation(x,y,z):
    x = input("Specify horizontal position: ")#latitude
    y = input("Specify vertical position: ")#longitude
    z = input("Specify altitude: ")#above sea level
    return x,y,z

def QuickTestMain():
##    x = 0
##    y = 0
##    z = 0
    getLocation(x,y,z)
    print("You are located at " + str(x) + "degrees latitude, " +
          str(y) + " degrees longitude, " + " and " + str(z) +
          " feet above sea level.")

QuickTestMain()

When lines 11 - 13 are not commented out, it just prints all 0's (I just wanted to initialize them, so that they exist in the program):

Error:
========== RESTART: I:/Python/Python36-32/SamsPrograms/QuickTest.py ==========
Specify horizontal position: 3
Specify vertical position: 4
Specify altitude: 5
You are located at 0degrees latitude, 0 degrees longitude,  and 0 feet above sea level.
>>>

And then if I comment them out, I get:

Error:
========== RESTART: I:/Python/Python36-32/SamsPrograms/QuickTest.py ==========
Traceback (most recent call last):
  File "I:/Python/Python36-32/SamsPrograms/QuickTest.py", line 19, in <module>
    QuickTestMain()
  File "I:/Python/Python36-32/SamsPrograms/QuickTest.py", line 14, in QuickTestMain
    getLocation(x,y,z)
NameError: name 'x' is not defined
>>>

How do I fix this?