Set the main dataframe with the content of an Excel file

        :param filepath: url of the csv file to load,
                        can be absolute if it starts with ``/``
                        or relative if it starts with ``./``
        :type filepath: str

        :param kwargs: keyword arguments to pass to 
                            Pandas ``read_excel`` function

        :example: ``ds.load_excel("./myfile.xlsx")``

def load_excel(self, filepath, **kwargs):
        """Set the main dataframe with the content of an Excel file

        :param filepath: url of the csv file to load,
                        can be absolute if it starts with ``/``
                        or relative if it starts with ``./``
        :type filepath: str

        :param kwargs: keyword arguments to pass to 
                            Pandas ``read_excel`` function

        :example: ``ds.load_excel("./myfile.xlsx")``
        """
        try:
            df = pd.read_excel(filepath, **kwargs)
            if len(df.index) == 0:
                self.warning("Empty Excel file. Can not set the dataframe.")
                return
            self.df = df
        except Exception as e:
            self.err(e, "Can not load Excel file")