old_contents: import subprocess
  
  # --- replacing shell backticks ---
  # https://docs.python.org/2/library/subprocess.html#replacing-bin-sh-shell-backquote
  #   output=`mycmd myarg`
  #   output = check_output(["mycmd", "myarg"])
  # not true, because mycmd is not passed to shell
  try:
      output = subprocess.check_output(["mycmd", "myarg"], shell=True)
  except OSError as ex:
      # command not found.
      # it is impossible to catch output here, but shell outputs
      # message to stderr, which backticks doesn't catch either
      output = ''
  except subprocess.CalledProcessError as ex:
      output = ex.output
  # ^ information about error condition is lost
  # ^ output in case of OSError is lost
  
  # ux notes:
  # - `mycmd myarg` > ["mycmd", "myarg"]
  # - `` is invisible
  #   subprocess.check_output is hardly rememberable
  # - exception checking is excessive and not needed
  #   (common pattern is to check return code)
  
  
  def backticks(command):
     '''
     Execute `command and return output.
     - no return code
     - no stderr capture
     - bailed out with MemoryError on Windows with 500Mb of output
     '''
     try:
         # this doesn't escape shell patterns, such as:
         # ^ (windows cmd.exe shell)
         output = subprocess.check_output(command, shell=True)
     except OSError as ex:
         # command not found.
         # it is impossible to catch output here, but shell outputs
         # message to stderr, which backticks doesn't catch either
         output = ''
     except subprocess.CalledProcessError as ex:
         output = ex.output
     return output
  
new_contents: import subprocess
  
  # --- replacing shell backticks ---
  # https://docs.python.org/2/library/subprocess.html#replacing-bin-sh-shell-backquote
  #   output=`mycmd myarg`
  #   output = check_output(["mycmd", "myarg"])
  # not true, because mycmd is not passed to shell
  try:
      output = subprocess.check_output(["mycmd", "myarg"], shell=True)
  except OSError as ex:
      # command not found.
      # it is impossible to catch output here, but shell outputs
      # message to stderr, which backticks doesn't catch either
      output = ''
  except subprocess.CalledProcessError as ex:
      output = ex.output
  # ^ information about error condition is lost
  # ^ output in case of OSError is lost
  
  # ux notes:
  # - `mycmd myarg` > ["mycmd", "myarg"]
  # - `` is invisible
  #   subprocess.check_output is hardly rememberable
  # - exception checking is excessive and not needed
  #   (common pattern is to check return code)
  
  
  def backticks(command):
     '''
     Execute `command` and return output.
     - no return code
     - no stderr capture
     - bailed out with MemoryError on Windows with 500Mb of output
     '''
     try:
         # this doesn't escape shell patterns, such as:
         # ^ (windows cmd.exe shell)
         output = subprocess.check_output(command, shell=True)
     except OSError as ex:
         # command not found.
         # it is impossible to catch output here, but shell outputs
         # message to stderr, which backticks doesn't catch either
         output = ''
     except subprocess.CalledProcessError as ex:
         output = ex.output
     return output
  
subject: fix backtick in backticks docstring