code: def namedb_get_all_revealed_namespace_ids( self, current_block ):
      
      
      query = "SELECT namespace_id FROM namespaces WHERE op = ? AND reveal_block < ?;"
      args = (NAMESPACE_REVEAL, current_block + NAMESPACE_REVEAL_EXPIRE )
  
      namespace_rows = namedb_query_execute( cur, query, args )
      ret = []
      for namespace_row in namespace_rows:
          ret.append( namespace_row['namespace_id'] )
  
      return ret
docs: Get all non-expired revealed namespaces.