help with python mouse clicks and Pygame

[Windspar]

Never get key pressed in event loop. When in event loop. Only use event items.
Example.

import pygame

def main():
    pygame.init()
    pygame.display.set_caption("Mouse Draw")
    surface = pygame.display.set_mode((800, 600))
    clock = pygame.time.Clock()
    rect = surface.get_rect()
    fps = 60

    line_surface = pygame.Surface(rect.size, pygame.SRCALPHA)
    line_surface.fill((0, 0, 0, 0))

    mouse_position = None
    display_line = None
    running = True
    while running:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                running = False
            elif event.type == pygame.MOUSEMOTION:
                if mouse_position:
                    display_line = mouse_position, event.pos
            elif event.type == pygame.MOUSEBUTTONDOWN:
                if event.button == 1:
                    if mouse_position:
                        pygame.draw.line(line_surface, pygame.Color("red"), mouse_position, event.pos)
                        mouse_position = None
                        display_line = None
                    else:
                        mouse_position = event.pos


        surface.fill(pygame.Color('black'))
        surface.blit(line_surface, (0, 0))

        if display_line:
            pygame.draw.line(surface, pygame.Color('lawngreen'), *display_line)

        pygame.display.update()
        clock.tick(fps)

main()

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If you want it to be continues lines. Change line 28.

mouse_position = event.pos