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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def boxplot(self, **vargs):
 """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. test1 | test2 92.5 | 89 88 | 84 72 | 74 71 | 66 99 | 92 100 | 99 95 | 88 83 | 81 94 | 95 93 | 94 <boxplot of test1 and boxplot of test2 side-by-side on the same figure> """

        # 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)