code: def _concat_sparse(to_concat, axis=0, typs=None):
      
  
      from pandas.core.arrays import SparseArray
  
      fill_values = [x.fill_value for x in to_concat
                     if isinstance(x, SparseArray)]
      fill_value = fill_values[0]
  
      # TODO: Fix join unit generation so we aren't passed this.
      to_concat = [x if isinstance(x, SparseArray)
                   else SparseArray(x.squeeze(), fill_value=fill_value)
                   for x in to_concat]
  
      return SparseArray._concat_same_type(to_concat)
docs: provide concatenation of an sparse/dense array of arrays each of which is a
      single dtype
  
      Parameters
      ----------
      to_concat : array of arrays
      axis : axis to provide concatenation
      typs : set of to_concat dtypes
  
      Returns
      -------
      a single array, preserving the combined dtypes