title: how to deal with feature that are not change over time when use RNN(LSTM)
body: <p>I build a model based on LSTM to predict sale of next day. most of features (eg: sale of day, number of customer) change over time. <strong>but there are some feature (eg: price of item) are not changing</strong>. 
  For now, I just feed all these data into LSTM. But I wonder for features that are not changing over time, is there a better way to deal with it? because I think RNN is designed to model temporal structure. </p>