code: def boxplot(self, **vargs):
          
          # Check for non-numerical values and raise a ValueError if any found
          for col in self:
              if any(isinstance(cell, np.flexible) for cell in self[col]):
                  raise ValueError("The column '{0}' contains non-numerical "
                      "values. A histogram cannot be drawn for this table."
                      .format(col))
  
          columns = self._columns.copy()
          vargs['labels'] = columns.keys()
          values = list(columns.values())
          plt.boxplot(values, **vargs)
docs: Plots a boxplot for the table.
  
          Every column must be numerical.
  
          Kwargs:
              vargs: Additional arguments that get passed into `plt.boxplot`.
                  See http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.boxplot
                  for additional arguments that can be passed into vargs. These include
                  `vert` and `showmeans`.
  
          Returns:
              None
  
          Raises:
              ValueError: The Table contains columns with non-numerical values.
  
          >>> table = Table().with_columns(
          ...     'test1', make_array(92.5, 88, 72, 71, 99, 100, 95, 83, 94, 93),
          ...     'test2', make_array(89, 84, 74, 66, 92, 99, 88, 81, 95, 94))
          >>> table
          test1 | test2
          92.5  | 89
          88    | 84
          72    | 74
          71    | 66
          99    | 92
          100   | 99
          95    | 88
          83    | 81
          94    | 95
          93    | 94
          >>> table.boxplot() # doctest: +SKIP
          <boxplot of test1 and boxplot of test2 side-by-side on the same figure>