code: def get_column(self, X, column):
          
          if isinstance(X, pd.DataFrame):
              return X[column].values
  
          return X[:, column]
docs: Return a column of the given matrix.
  
          Args:
              X: `numpy.ndarray` or `pandas.DataFrame`.
              column: `int` or `str`.
  
          Returns:
              np.ndarray: Selected column.