old_contents: #!/usr/bin/python
  # -*- coding: utf-8 -*-
  import subprocess
  import itertools
  
  class SerialFinder():
      _command = """ls -al /sys/class/tty/ttyUSB* | grep -o "/sys/class/tty/ttyUSB.*"| sed 's/ -> .*//'"""
      _replace = "/sys/class/tty"
      _replaceWith = "/dev"
  
  
      def Find(self):
  
          proc = subprocess.Popen([self._command], stdout=subprocess.PIPE, shell=True)
          (out, err) = proc.communicate()
  
          if len(out) < 2:
              return None
  
          return self.__split(out)
  
      def __groupSeparator(self, line):
          return line=='\n'
  
      def __split(self, data):
          lines = []
          for key, group in itertools.groupby(data, self.__groupSeparator):
              line = ''.join(str(e) for e in group)
              line = line.strip()
              if (len(line) > 1):
                  lines.append(line.replace(self._replace, self._replaceWith))
          return lines
  
new_contents: #!/usr/bin/python
  # -*- coding: utf-8 -*-
  import subprocess
  import itertools
  
  class SerialFinder():
      _command = """ls -al /sys/class/tty/ttyUSB* | grep -o "/sys/class/tty/ttyUSB.*"| sed 's/ -> .*//'"""
      _replace = "/sys/class/tty"
      _replaceWith = "/dev"
  
  
      def Find(self):
          proc = subprocess.Popen([self._command], stdout=subprocess.PIPE, shell=True)
          (out, err) = proc.communicate()
  
          if len(out) < 2:
              return []
  
          return self.__split(out)
  
      def __groupSeparator(self, line):
          return line=='\n'
  
      def __split(self, data):
          lines = []
          for key, group in itertools.groupby(data, self.__groupSeparator):
              line = ''.join(str(e) for e in group)
              line = line.strip()
              if (len(line) > 1):
                  lines.append(line.replace(self._replace, self._replaceWith))
          return lines
  
subject: fix finder return value