Program won't run
<p>I have this exercise and the first part of the program was running fine but I must've done something because now when I try to run it will just show <code>None</code> and and nothing seems to be 'wrong'. I don't know enough to even figure out what's wrong.</p>

<pre><code>def main():
    """Gets the job done"""

#this program returns the value according to the colour
def re_start():
    #do the work
    return read_colour

def read_names():
    """prompt user for their name and returns in a space-separaded line"""
    PROMPT_NAMES = input("Enter names: ")
    users_names = '{}'.format(PROMPT_NAMES)
    print (users_names)
    return users_names

def read_colour():
    """prompt user for a colour letter if invalid colour enter retry"""
    ALLOWED_COLOURS = ["whero",
               "kowhai",
               "kikorangi",
               "parauri",
               "kiwikiwi",
               "karaka",
               "waiporoporo",
               "pango"]
    PROMPT_COLOUR = input("Enter letter colour: ").casefold()

    if PROMPT_COLOUR in ALLOWED_COLOURS:
        return read_names()

    else:
        print("Invalid colour...")
        print(*ALLOWED_COLOURS,sep='\n')
        re_start()
main()
</code></pre>

<p>The only function you call is <code>main()</code>, but that has no statements in it, so your code will do nothing. To fix this, put some statements in your <code>main()</code> and rerun your code.</p>

python python-3.x