code: def find_package_indexes_in_dir(self, simple_dir):
          
          packages = sorted(
              {
                  # Filter out all of the "non" normalized names here
                  canonicalize_name(x)
                  for x in os.listdir(simple_dir)
              }
          )
          # Package indexes must be in directories, so ignore anything else.
          packages = [x for x in packages if os.path.isdir(os.path.join(simple_dir, x))]
          return packages
docs: Given a directory that contains simple packages indexes, return
          a sorted list of normalized package names.  This presumes every
          directory within is a simple package index directory.