Fix imports and random seed

combo/modules/seq2seq_encoders/transformer_encoder.py

 from typing import Optional
 
-from overrides import overrides
 import torch
 from torch import nn
 
 from combo.modules.encoder import _EncoderBase
 from combo.config.from_parameters import FromParameters, register_arguments
-
-# from modules.seq2seq_encoders.seq2seq_encoder import Seq2SeqEncoder
-from nn.utils import add_positional_features
-
-
-# from allennlp.modules.seq2seq_encoders.seq2seq_encoder import Seq2SeqEncoder
-# from allennlp.nn.util import add_positional_features
+from combo.nn.utils import add_positional_features
 
 
 class TransformerEncoder(_EncoderBase, FromParameters):