code: def dummies_time(self):
      self.dummy_sparse(level=1)
      return self._dummies
  
imports: from statsmodels.compat.python import lrange, lzip
  import numpy
  import pandas
  import statsmodels.tools.data
  from pandas import Index, MultiIndex
label_desc: Use image node_id 14 for calling the Grouping obj's underlying member method code with example usage: obj.dummies_time() and returns: self