code: def review_metadata_csv_multi_user(filedir, metadata, csv_in, n_headers):
      
      try:
          if not validate_subfolders(filedir, metadata):
              return False
          for project_member_id, member_metadata in metadata.items():
              if not validate_metadata(os.path.join
                                       (filedir, project_member_id),
                                       member_metadata):
                  return False
              for filename, file_metadata in member_metadata.items():
                  is_single_file_metadata_valid(file_metadata, project_member_id,
                                                filename)
  
      except ValueError as e:
          print_error(e)
          return False
      return True
docs: Check validity of metadata for multi user.
  
      :param filedir: This field is the filepath of the directory whose csv
          has to be made.
      :param metadata: This field is the metadata generated from the
          load_metadata_csv function.
      :param csv_in: This field returns a reader object which iterates over the
          csv.
      :param n_headers: This field is the number of headers in the csv.