class Toks():   
    UNK = 0
    BOS = 1 #beginning of sentence
    EOS = 2 #end of sentence


NEGATIVE_SAMPLING_NUM = 10
IN_TO_OUT_UNITS_RATIO = 2
SENT_COUNTS_FILENAME = 's_counts'    
WORD_COUNTS_FILENAME = 'w_counts'
TOTAL_COUNTS_FILENAME = 'totals'