Im making a Pygame called mooshalot scape my game is not opening, would really appreciate a look at my code

Question

Im a beginner pygameneer and im making this sweet space invaders type game called mooshalot escape, the point being that you will get to become a mooshalot and fight the evils that threaten the condition of the mooshalots, its a self project to help me become a better programmer, (of course its a free game so when done ill post it lols) The point being I'm having trouble opening my game, the code runs properly, but the screen is the main issue, I don't think I did a good job connecting the screen, could someone take a look would really appreciate the help and input in any shape or format, regards

import sys

import pygame

from settings import Settings
from Mooshipclassr import Mooship
from Mooshammo import Mooshammo


class MooshalotEscape:

    def __init__(self):
        pygame.init()
        self.settings = Settings()
        self.screen = pygame.display.set_mode((0, 0), pygame.FULLSCREEN)
        self.settings.screen_width = self.screen.get_rect().width
        self.settings.screen_height = self.screen.get_rect().height
        pygame.display.set_caption('Mooshalot Escape')
        self.bg_color = (106, 228, 241)
        self.mooship = Mooship(self)
        self.bullets = pygame.sprite.Group()

    def run_game(self):
        while True:
            self._check_events()
            self.mooship.update()
            self.bullets.update()
            self._update_screen()

    def _check_events(self):
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                sys.exit()
            elif event.type == pygame.KEYDOWN:
                self._check_keydown_events(event)
            elif event.type == pygame.KEYUP:
                self._check_keyup_events(event)

    def _check_keydown_events(self, event):
        if event.key == pygame.K_RIGHT:
            self.mooship.moving_right = True
        elif event.key == pygame.K_LEFT:
            self.mooship.moving_left = True
        elif event.key == pygame.K_q:
            sys.exit()
        elif event.key == pygame.K_SPACE:
            self._fire_mooshammo()

    def _check_keyup_events(self, event):
        if event.key == pygame.K_RIGHT:
            self.mooship.moving_right = False
        elif event.key == pygame.K_LEFT:
            self.mooship.moving_left = False

    def _fire_mooshammo(self):
        new_mooshammo = Mooshammo(self)
        self.bullets.add(new_mooshammo)

    def _update_screen(self):
        self.screen.fill(self.bg_color)
        self.mooship.blitme()

        pygame.display.flip()


if __name__ == 'main':
    ai = MooshalotEscape()
    ai.run_game()


'''settings class'''

    class Settings:
    def __init__(self):
        self.screen_width = 1200
        self.screen_height = 800
        self.bg_color = (106, 228, 241)
        self.mooship_speed = 1.5
        self.mooshammo_speed = 1.0
        self.mooshammo_width = 3
        self.mooshammo_height = 15
        self.mooshammo_color = (60, 60, 60)