<SYSTEM_TASK:>
Given the following text description, write Python code to implement the functionality described below step by step
<END_TASK>
<USER_TASK:>
Description:
 <img align="right" src="../img/exercise_distance_240.png" />
Exercise
Step1:  3. Motion code
In the following program template, you must fill the gaps with the appropriate code.
The idea is to compute the turned angle of one of the encoders (no matter which one) as the difference between the current and initial values, then compute the traveled distance. The robot will move as long as this distance is lower than the target distance, then it will stop.
Step2:  Solution
<ASSISTANT_TASK:>
Python Code:
import packages.initialization
import pioneer3dx as p3dx
p3dx.init()
Explanation: <img align="right" src="../img/exercise_distance_240.png" />
Exercise: Move the robot forward for a distance.
You are going to make a program for moving the robot forward from the initial position at the start of the simulation, in the center of the room.
The robot should stop after traveling a distance equal to the size of the tile, which is 2 m.
According to the specifications, the diameter of the wheels of the Pioneer 3DX robot is 195.3 mm.
1. Starting position
For a better visual understanding of the task, it is recommended that the robot starts at the center of the room. 
You can easily relocate the robot there by simply restarting the simulation.
2. Initialization
After restarting the simulation, the robot needs to be initialized.
End of explanation
target = ...      # target distance
r = ...           # wheel radius
initialEncoder = ...
distance = 0
while distance < target:
    p3dx.move(2.5,2.5)
    angle = ...
    distance = ...
p3dx.move(0,0)
Explanation: 3. Motion code
In the following program template, you must fill the gaps with the appropriate code.
The idea is to compute the turned angle of one of the encoders (no matter which one) as the difference between the current and initial values, then compute the traveled distance. The robot will move as long as this distance is lower than the target distance, then it will stop.
End of explanation
target = 2.0      # target distance
r = 0.1953 / 2    # wheel radius
initialEncoder = p3dx.rightEncoder
distance = 0
while distance < target:
    p3dx.move(2.5,2.5)
    angle = p3dx.rightEncoder - initialEncoder
    distance = angle * r
p3dx.move(0,0)
Explanation: Solution
End of explanation
<END_TASK>