My EV3 can't run that. Can anyone help?

[TEDPOWERTRAIN]

I am pretty new to ev3 micropython and I don't know why my code doesn't work. This code is for exploring a maze.

#!/usr/bin/env pybricks-micropython

from pybricks.hubs import EV3Brick
from pybricks.ev3devices import Motor, UltrasonicSensor, TouchSensor
from pybricks.parameters import Port
from pybricks.robotics import DriveBase
import time

# Initialize the EV3 brick and sensors.
ev3 = EV3Brick()
left_motor = Motor(Port.A)
right_motor = Motor(Port.D)
left_distance_sensor = UltrasonicSensor(Port.S1)
right_distance_sensor = UltrasonicSensor(Port.S4)
front_touch_sensor = TouchSensor(Port.S2)

# Constants
FORWARD_SPEED = 100
REVERSE_SPEED = -100
WALL_DISTANCE_THRESHOLD = 200
REVERSE_DISTANCE = -100
SCAN_DISTANCE = 200  # Distance the robot moves forward to scan
WALL_SCAN_DURATION = 2  # Duration of the scanning phase in seconds
WALL_DISTANCE_THRESHOLD_DELTA = 12  # Threshold for difference in distances to mark as a wall

# Initialize the drive base.
robot = DriveBase(left_motor, right_motor, wheel_diameter=55.5, axle_track=104)

# Initialize SLAM variables
robot_pose = (0, 0)  # Initial pose of the robot (x, y)
map_belief = {}  # Initialize belief about the environment map
wall_locations = []  # Store wall locations for post-processing

# Function to move the robot forward
def move_forward():
    global robot_pose
    robot.straight(SCAN_DISTANCE) 
    # Update robot pose after moving forward
    robot_pose = (robot_pose[0], robot_pose[1] + 1)

# Function to turn the robot 90 degrees to the right
def turn_right():
    global robot_pose
    robot.turn(90)
    robot.straight(SCAN_DISTANCE) 
    # Update robot pose after turning right
    robot_pose = (robot_pose[0] + 1, robot_pose[1])

# Function to turn the robot 90 degrees to the left
def turn_left():
    global robot_pose
    robot.turn(-90)
    robot.straight(SCAN_DISTANCE) 
    # Update robot pose after turning left
    robot_pose = (robot_pose[0] - 1, robot_pose[1])

# Function to scan the environment and update the map belief
def scan_environment():
    global map_belief, wall_locations
    left_distance = left_distance_sensor.distance()
    right_distance = right_distance_sensor.distance()
    # Update map belief based on sensor readings
    if left_distance < WALL_DISTANCE_THRESHOLD:
        map_belief[(robot_pose[0] - 1, robot_pose[1])] = "Left Wall"
        wall_locations.append((robot_pose[0] - 1, robot_pose[1]))
    if right_distance < WALL_DISTANCE_THRESHOLD:
        map_belief[(robot_pose[0] + 1, robot_pose[1])] = "Right Wall"
        wall_locations.append((robot_pose[0] + 1, robot_pose[1]))

# Function to perform SLAM algorithm
def slam_algorithm():
    # Main mapping loop
    while True:
        robot.drive()  # Move forward until obstacle is detected
        robot.straight(REVERSE_DISTANCE)  # Move backward to allow space for turning
        robot.turn(95)  # Turn 90 degrees
        robot.drive()  # Move forward again
        robot.straight(REVERSE_DISTANCE)  # Move backward to allow space for turning
        robot.turn(-95)  # Turn back to the original direction
        scan_environment()  # Scan the environment and update the map belief

def print_map_belief():
    print("Map Belief:")
    for cell, content in map_belief.items():
        print("Cell {}: {}".format(cell, content))
# Function to save wall locations to a file
def save_wall_locations():
    with open("wall_locations.txt", "w") as file:
        for location in wall_locations:
            file.write("{}, {}\n".format(location[0], location[1]))            

[BertLindeman]

Hi Ted (I assume 😃 )

Could you update your post to better format your source?

If you put ```python
before your source
and ``` after it, then we can better read or copy your source.
[EDIT]: Thank you David.

Thanks,

Bert

[EDIT} And specifically indicate what does not "work".

[BertLindeman]

What I see is only function definitions.

Is this the complete program, or is there missing a part at the end?