Fix Python API.

Author: qingqing01

python/paddle/v2/framework/layers.py

@@ -372,11 +372,13 @@ def sequence_pool(input, pool_type, **kwargs):
  helper = LayerHelper('sequence_pool', input=input, **kwargs)
  dtype = helper.input_dtype()
  pool_out = helper.create_tmp_variable(dtype)
+ max_index = helper.create_tmp_variable(dtype)
 
  helper.append_op(
  type="sequence_pool",
- inputs={"X": [input]},
- outputs={"Out": [pool_out]},
+ inputs={"X": input},
+ outputs={"Out": pool_out,
+ "MaxIndex": max_index},
  attrs={"pooltype": pool_type.upper()})
 
  return pool_out