code: def set_cols_dtype(self, array):
          
  
          self._check_row_size(array)
          self._dtype = array
          return self
docs: Set the desired columns datatype for the cols.
  
          - the elements of the array should be either a callable or any of
            "a", "t", "f", "e" or "i":
  
              * "a": automatic (try to use the most appropriate datatype)
              * "t": treat as text
              * "f": treat as float in decimal format
              * "e": treat as float in exponential format
              * "i": treat as int
              * a callable: should return formatted string for any value given
  
          - by default, automatic datatyping is used for each column