module functions and data references

[Skaperen]

suppose you have a some functions in a module and two of these functions need to call the other functions. you need to call those two functions in a script.

an example module (named callers.py) to test this concept:

from __future__ import division, print_function

def a():
    print('this is a')
    return

def b():
    print('this is b')
    return

def c():
    print('this is c')
    return

def d():
    print('this is d')
    return

def x():
    print('this is x')
    a()
    b()
    return

def y():
    print('this is y')
    c()
    d()
    return

an example script that uses this:

from __future__ import division, print_function

from callers import x, y

x()
print('foobar')
y()

if you run this example script with this example module, the expected output is:

Output:
this is x
this is a
this is b
foobar
this is y
this is c
this is d

my question is: how are functions a,b,c, and d referenced if only x and y are imported.  i do understand (because i read it somewhere) that when "from somemodule import ..." is used, the whole module gets imported somewhere and the particular names being used are inserted into the importer script.  how do x and y find a,b,c, and d? where are the names placed?