old_contents: 
  
  import sys
  from time import time
  
  
  class PID(object):
  
      def __init__(self):
          """initizes value for the PID"""
          self.kd = 0
          self.ki = 0
          self.kp = 1
          self.previous_error = 0
          self.integral_error = 0
  
      def set_k_values(self, kp, kd, ki):
          self.kp = kp
          self.ki = ki
          self.kd = kd
  
      def pid(self, target, process_var, timestep):
          current_error = (target - process_var)
          p_error = self.kp * current_error
          d_error = self.kd * (current_error - self.previous_error) \
              / timestep
          self.integral_error = (
              current_error + self.previous_error) / 2 \
              + self.integral_error
          i_error = self.ki * self.integral_error
          total_error = p_error + d_error + i_error
          self.previous_error = current_error
          return total_error
  
new_contents: 
  
  import sys
  from time import time
  
  
  class PID(object):
  
      def __init__(self):
          """initizes value for the PID"""
          self.kd = 0
          self.ki = 0
          self.kp = 1
          self.previous_error = 0
          self.integral_error = 0
  
      def set_k_values(self, kp, kd, ki):
          self.kp = kp
          self.ki = ki
          self.kd = kd
  
      def pid(self, target, process_var, timestep):
          current_error = (target + process_var)
          p_error = self.kp * current_error
          d_error = self.kd * (current_error - self.previous_error) \
              / timestep
          self.integral_error = (
              current_error + self.previous_error) / 2 \
              + self.integral_error
          i_error = self.ki * self.integral_error
          total_error = p_error + d_error + i_error
          self.previous_error = current_error
          return total_error
  
subject: Update to follower, reduce speed to motors.