code: def listFileChildren(self, logical_file_name='', block_name='', block_id=0):
          
          conn = self.dbi.connection()
          try:
              if not logical_file_name and not block_name and not block_id:
                  dbsExceptionHandler('dbsException-invalid-input',\
                          "Logical_file_name, block_id or block_name is required for listFileChildren api")
              sqlresult = self.filechildlist.execute(conn, logical_file_name, block_name, block_id)
              d = {}
              result = []
              for i in range(len(sqlresult)):
                  k = sqlresult[i]['logical_file_name']
                  v = sqlresult[i]['child_logical_file_name']
                  if k in d:
                      d[k].append(v)
                  else:
                      d[k] = [v]
              for k, v in d.iteritems():
                  r = {'logical_file_name':k, 'child_logical_file_name': v}
                  result.append(r)
              return result
          finally:
              if conn:
                  conn.close()
docs: required parameter: logical_file_name or block_name or block_id
          returns: logical_file_name, child_logical_file_name, parent_file_id