def sum(self, axis=<NUM_LIT:0>, *args, **kwargs):
nv.validate_sum(args, kwargs)<EOL>valid_vals = self._valid_sp_values<EOL>sp_sum = valid_vals.sum()<EOL>if self._null_fill_value:<EOL><INDENT>return sp_sum<EOL><DEDENT>else:<EOL><INDENT>nsparse = self.sp_index.ngaps<EOL>return sp_sum + self.fill_value * nsparse<EOL><DEDENT>
Sum of non-NA/null values

Returns
-------
sum : float