old_contents: #!/bin/python3
  """ This script contains functions to access various system's info.
  
      Author: Julien Delplanque
  """
  import subprocess
  
  def get_uptime():
      """ Return the uptime of the system as a str using the command: $ uptime
      """
      proc = subprocess.Popen(["uptime"], stdout=subprocess.PIPE, shell=True)
      (output, error) = proc.communicate()
      uptime = output.decode("utf-8").split()[2]
      uptime = uptime[0:len(uptime)-2] # remove the comma
      return uptime
  
new_contents: #!/bin/python3
  """ This script contains functions to access various system's info.
  
      Author: Julien Delplanque
  """
  import subprocess
  
  def get_uptime():
      """ Return the uptime of the system as a str using the command: $ uptime
      """
      proc = subprocess.Popen(["uptime"], stdout=subprocess.PIPE, shell=True)
      (output, error) = proc.communicate()
      uptime = output.decode("utf-8").split(",")[0]
      uptime = uptime[uptime.find("up")+3:len(uptime)] # extract uptime
      return uptime
  
subject: Correct get_uptime function. It didn't extract the uptime correctly. Now it does.