Get all pull requests of a project.
        :param status: filters the status of the requests
        :param assignee: filters the assignee of the requests
        :param author: filters the author of the requests
        :return:

def list_requests(self, status=None, assignee=None, author=None):
        """
        Get all pull requests of a project.
        :param status: filters the status of the requests
        :param assignee: filters the assignee of the requests
        :param author: filters the author of the requests
        :return:
        """
        request_url = "{}pull-requests".format(self.create_basic_url())

        payload = {}
        if status is not None:
            payload['status'] = status
        if assignee is not None:
            payload['assignee'] = assignee
        if author is not None:
            payload['author'] = author

        return_value = self._call_api(request_url, params=payload)
        return return_value['requests']