code: def check_if_exiftool_is_already_installed():
      
      result = 1;
      command = ["exiftool", "-ver"]
  
      with open(os.devnull, "w") as fnull:
          result = subprocess.call(
              command,
              stdout = fnull,
              stderr = fnull
          )
      #Exiftool is not installed
      if result != 0:
          print_a_header('Exiftool needs to be installed on your system')
          print_a_header('Visit http://www.sno.phy.queensu.ca/~phil/exiftool/')
          return False
      else:
          return True
docs: Requirements
  
      This function will check if Exiftool is installed
      on your system
  
      Return: True if Exiftool is Installed
              False if not