<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_default_master_type(num_gpus=1):
 """Returns master_type for trainingInput."""

  gpus_to_master_map = {
      0: "standard",
      1: "standard_p100",
      4: "complex_model_m_p100",
      8: "complex_model_l_gpu",
  }
  if num_gpus not in gpus_to_master_map:
    raise ValueError("Num gpus must be in %s" %
                     str(sorted(list(gpus_to_master_map.keys()))))
  return gpus_to_master_map[num_gpus]