code: def idxmin(self, axis=0, skipna=True):
          
          axis = self._get_axis_number(axis)
          indices = nanops.nanargmin(self.values, axis=axis, skipna=skipna)
          index = self._get_axis(axis)
          result = [index[i] if i >= 0 else np.nan for i in indices]
          return Series(result, index=self._get_agg_axis(axis))
docs: Return index of first occurrence of minimum over requested axis.
          NA/null values are excluded.
  
          Parameters
          ----------
          axis : {0 or 'index', 1 or 'columns'}, default 0
              0 or 'index' for row-wise, 1 or 'columns' for column-wise
          skipna : boolean, default True
              Exclude NA/null values. If an entire row/column is NA, the result
              will be NA.
  
          Returns
          -------
          Series
              Indexes of minima along the specified axis.
  
          Raises
          ------
          ValueError
              * If the row/column is empty
  
          See Also
          --------
          Series.idxmin
  
          Notes
          -----
          This method is the DataFrame version of ``ndarray.argmin``.