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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 full_name(self):
 """ Returns the first and last name of the user separated by a space. """

        formatted_user = []
        if self.user.first_name is not None:
            formatted_user.append(self.user.first_name)
        if self.user.last_name is not None:
            formatted_user.append(self.user.last_name)
        return " ".join(formatted_user)