def nvalues(self):
        """Returns the number of values recorded on this single line. If the
        number is variable, it returns -1."""
        if self._nvalues is None:
            self._nvalues = 0
            for val in self.values:
                if type(val) == type(int):
                    self._nvalues += val
                else:
                    self._nvalues = -1
                    break

        return self._nvalues
def nvalues ( self ) : if self . _nvalues is None : self . _nvalues = 0 for val in self . values : if type ( val ) == type ( int ) : self . _nvalues += val else : self . _nvalues = - 1 break return self . _nvalues
Returns the number of values recorded on this single line. If the
        number is variable, it returns -1.