old_contents: # Write a program that opens all .txt files in a folder and searches for any line
  # that matches a user-supplied regular expression.
  #
  # The results should be printed to the screen.
  import os, re
  
  # Get list of all .txt files
  all_files = os.listdir("./")  # use current working directory
  text_files = []
  for file in all_files:
      if file.endswith(".txt"):
          text_files.append(file)
  
  # Get regular expression
  regex = input("Enter regular expression to search for: ")
  search_regex = re.compile(regex)
  
  # Open .txt file
  for file in text_files:
      input_file = open(file)
      input_content = input_file.readlines()
      input_file.close()
  
      # Search for regex in file
      for line in input_content:
          match_objects = search_regex.findall(line)
          if match_objects is not None:
              # Print result
              for match in match_objects:
                  print(match)
  
new_contents: """Regex search
  
  Write a program that opens all .txt files in a folder and searches for any line
  that matches a user-supplied regular expression.
  
  The results should be printed to the screen.
  
  """
  
  
  def main():
      import os, re
  
      # Get list of all .txt files
      all_files = os.listdir("./")  # use current working directory
      text_files = []
      for file in all_files:
          if file.endswith(".txt"):
              text_files.append(file)
  
      # Get regular expression
      regex = input("Enter regular expression to search for: ")
      search_regex = re.compile(regex)
  
      # Open .txt file
      for file in text_files:
          input_file = open(file)
          input_content = input_file.readlines()
          input_file.close()
  
          # Search for regex in file
          for line in input_content:
              match_objects = search_regex.findall(line)
              if match_objects is not None:
                  # Print result
                  for match in match_objects:
                      print(match)
  
  
  if __name__ == '__main__':
      main()
  
subject: Update P3_regexSearch.py added docstring and wrapped in main() function