Return the [first] [v]alue or the value given by the keyword
        argument `default` if not value exists. `default` defaults to `None`.

def firstvalue(self, *fieldspecs, **kwargs):
        """
        Return the [first] [v]alue or the value given by the keyword
        argument `default` if not value exists. `default` defaults to `None`.
        """
        default = kwargs.get('default', None)
        values = [val for val in self.itervalues(*fieldspecs, **kwargs)]
        if values:
            return values[0]
        else:
            return default