Pololu 3Pi Robot follow a line

/*
Here's an example code for making the Pololu 3Pi Robot follow a line using an Arduino:

Note that this code assumes a black line on a white background. If your line is white on a black background, you will need to modify the read_line function call to use IR_EMITTERS_OFF instead of IR_EMITTERS_ON. Additionally, you may need to adjust the calibration values and the proportional_control function to optimize the line following behavior for your specific line.
*/

#include <Pololu3pi.h>

void setup() {
  // Set up the 3Pi Robot
  initialize();

  // Set the maximum speed for the motors
  set_max_speed(60);

  // Calibrate the sensors for line following
  calibrate_line_sensors(IR_EMITTERS_ON);
}

void loop() {
  // Read the sensor values and determine the motor speeds
  unsigned int sensors[5];
  read_line(sensors, IR_EMITTERS_ON);
  int position = line_position(sensors);
  int speedDifference = proportional_control(position);

  // Set the motor speeds based on the sensor readings
  int leftSpeed = 60 + speedDifference;
  int rightSpeed = 60 - speedDifference;
  set_motors(leftSpeed, rightSpeed);
}

// Calculate the proportional control signal based on the sensor readings
int proportional_control(int position) {
  int error = position - 2000; // Center position is 2000
  int speedDifference = error / 4;
  return speedDifference;
}