code: def recursive_find_search(folder_path, regex=''):
      
      outlist = []
      for root, dirs, files in os.walk(folder_path):
          outlist.extend([op.join(root, f) for f in files
                          if re.search(regex, f)])
  
      return outlist
docs: Returns absolute paths of files that match the regex within file_dir and
      all its children folders.
  
      Note: The regex matching is done using the search function
      of the re module.
  
      Parameters
      ----------
      folder_path: string
  
      regex: string
  
      Returns
      -------
      A list of strings.