old_contents: #!/usr/bin/env python
  # Downloads some of the OnTime flights database
  # pylint: disable=invalid-name,missing-docstring
  
  import os
  import subprocess
  
  def execute_command(command):
      """Executes the specified command using a shell"""
      print(command)
      exitcode = subprocess.call(command, shell=True)
      if exitcode != 0:
          print("Exit code returned:", exitcode)
          exit(exitcode)
  
  def canonical_name(year, month):
      return "On_Time_On_Time_Performance_" + str(year) + "_" + str(month)
  
  def download(startyear, startmonth, endyear, endmonth):
      months = (endyear - startyear) * 12 + endmonth - startmonth + 1
      if months < 0:
          print("Illegal time range")
      for i in range(0, months):
          inMonths = startyear*12 + startmonth + i - 1
          year = inMonths / 12
          month = (inMonths % 12) + 1
          if year >= 2018:
              basename = "On_Time_Reporting_Carrier_On_Time_Performance_1987_present_" + str(year) + "_" + str(month)
          else:
              # Unfortunately currently the website no longer has these files and it is not
              # clear what name they should have
              basename = "On_Time_On_Time_Performance_" + str(year) + "_" + str(month)
          canonical = canonical_name(year, month)
          if not os.path.exists(canonical + ".csv.gz"):
              filename = basename + ".zip"
              url = "https://transtats.bts.gov/PREZIP/" + filename
              execute_command("wget -q " + url)
              execute_command("unzip -o " + filename)
              os.unlink(filename)
              os.unlink("readme.html")
              actualname = basename.replace("1987_present", "(1987_present)")
              os.rename(actualname + ".csv", canonical + ".csv")
              execute_command("gzip " + canonical + ".csv")
          else:
              print("Already having " + basename)
  
  def main():
      download(2018, 1, 2018, 2)
  
  if __name__ == "__main__":
      main()
  
new_contents: #!/usr/bin/env python
  # Downloads some of the OnTime flights database
  # pylint: disable=invalid-name,missing-docstring
  
  import os
  import subprocess
  
  def execute_command(command):
      """Executes the specified command using a shell"""
      print(command)
      exitcode = subprocess.call(command, shell=True)
      if exitcode != 0:
          print("Exit code returned:", exitcode)
          exit(exitcode)
  
  def canonical_name(year, month):
      return "On_Time_On_Time_Performance_" + str(year) + "_" + str(month)
  
  def download(startyear, startmonth, endyear, endmonth):
      months = (endyear - startyear) * 12 + endmonth - startmonth + 1
      if months < 0:
          print("Illegal time range")
      for i in range(0, months):
          inMonths = startyear*12 + startmonth + i - 1
          year = inMonths / 12
          month = (inMonths % 12) + 1
          basename = "On_Time_Reporting_Carrier_On_Time_Performance_1987_present_" + str(year) + "_" + str(month)
          canonical = canonical_name(year, month)
          if not os.path.exists(canonical + ".csv.gz"):
              filename = basename + ".zip"
              url = "https://transtats.bts.gov/PREZIP/" + filename
              execute_command("wget -q " + url)
              execute_command("unzip -o " + filename)
              os.unlink(filename)
              os.unlink("readme.html")
              actualname = basename.replace("1987_present", "(1987_present)")
              os.rename(actualname + ".csv", canonical + ".csv")
              execute_command("gzip " + canonical + ".csv")
          else:
              print("Already having " + basename)
  
  def main():
      download(2018, 1, 2018, 2)
  
  if __name__ == "__main__":
      main()
  
subject: Fix for issue #429