docs: def list_filepaths(self, wildcard=None):
          """
          Return the list of absolute filepaths in the directory.
  
          Args:
              wildcard: String of tokens separated by "|". Each token represents a pattern.
                  If wildcard is not None, we return only those files that match the given shell pattern (uses fnmatch).
                  Example:
                    wildcard="*.nc|*.pdf" selects only those files that end with .nc or .pdf
          """
          # Select the files in the directory.
          fnames = [f for f in os.listdir(self.path)]
          filepaths = filter(os.path.isfile, [os.path.join(self.path, f) for f in fnames])
  
          # Filter using the shell patterns.
          if wildcard is not None:
              filepaths = WildCard(wildcard).filter(filepaths)
  
          return filepaths