pygame key pressed once

1import pygame
2events = pygame.event.get()
3for event in events:
4    if event.type == pygame.KEYDOWN:
5        if event.key == pygame.K_LEFT:
6            location -= 1
7        if event.key == pygame.K_RIGHT:
8            location += 1
9

1# Outside loop
2pressed = False
3
4# Inside loop
5if event.type == pygame.KEYDOWN:
6	if event.key == pygame.K_a and not pressed: #K_a can be replaced by any key
7		# Do something
8		pressed = True
9	elif event.key != pygame.K_a:
10    	pressed = False