def values(self):
        """Return data in `self` as a numpy array.

        If all columns are the same dtype, the resulting array
        will have this dtype. If there are >1 dtypes in columns,
        then the resulting array will have dtype `object`.
        """
        dtypes = [col.dtype for col in self.columns]
        if len(set(dtypes)) > 1:
            dtype = object
        else:
            dtype = None
        return np.array(self.columns, dtype=dtype).T
Return data in `self` as a numpy array.

        If all columns are the same dtype, the resulting array
        will have this dtype. If there are >1 dtypes in columns,
        then the resulting array will have dtype `object`.