Type error: dump() missing 1 required positional argument: fp

[jaycuff13]

Hi, I am trying to create a json file that stores my users email for subscription purposes. I get an error that says, 'Type error: dump() missing 1 required positional'. Here is my code:

print('Welcome to the Urban ')

import json

import username

import favartist


def userfav():
    userfav = input('Please select your favorite artist: \n ')
    a = 'Yes' or 'yes'
    ab = 'No' or 'no'
    if userfav == 'Drake':
        subs = input('Would you like to subscribe to notifications for Drake?:')
        if subs == a:
            print('Thank you for subscribing')
        elif subs == ab:
            print('You ca subscribe later')
        else:
            print('Selection is invalid')
    elif userfav == 'J.Cole':
        subs = input('Would you like to subscribe to notifications for J.Cole?:')
        if subs == a:
            print('Thank you for subscribing')
        elif subs == ab:
            print('You ca subscribe later')
        else:
            print('Selection is invalid')

    elif userfav == 'Anderson Paak':
        subs = input('Would you like to subscribe to notifications for Drake?:')
        if subs == a:
            print('Thank you for subscribing')
            ussubem()
        elif subs == ab:
            print('You ca subscribe later')
        else:
            print('Selection is invalid')


userfav()

def ussubem():
    userfav = True
    a = True
    sub_e = input('Please enter your subscription email: \n ')
    em = sub_e
    return print('Thank you, will now receive regular emails about The Urban Macchiato to,' + sub_e)

ussubem()

with open('usersub.json', 'w+') as json_file:
    json.dump(ussubem)