code: def grep(pattern, *files_or_paths):
      
      matches = []
  
      for fop in files_or_paths:
          with fileobj(fop) as fo:
              matches.extend((line for line in fo if re.match(pattern, line)))
  
      return matches
docs: Returns lines matched in fnames, where fnames can either be pathnames to
      files to grep through or open file objects to grep through line by line