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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fill(self, field, value):
 """ Fill a specified form field in the current document. :param field: an instance of :class:`zombie.dom.DOMNode` :param value: any string value :return: self to allow function chaining. """

        self.client.nowait('browser.fill', (field, value))
        return self