code: def drop_nan(self, col: str=None, method: str="all", **kwargs):
          
          try:
              if col is None:
                  self.df = self.df.dropna(how=method, **kwargs)
              else:
                  self.df = self.df[self.df[col].notnull()]
          except Exception as e:
              self.err(e, "Error dropping nan values")
docs: Drop rows with NaN values from the main dataframe
  
          :param col: name of the column, defaults to None. Drops in 
                                                                                                                                                                                                          all columns if no value is provided
          :type col: str, optional
          :param method: ``how`` param for ``df.dropna``, defaults to "all"
          :type method: str, optional
          :param \*\*kwargs: params for ``df.dropna``
          :type \*\*kwargs: optional
  
          :example: ``ds.drop_nan("mycol")``