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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 create(self, project_id=None):
 """Creates the bucket. Args: project_id: the project in which to create the bucket. Returns: The bucket. Raises: Exception if there was an error creating the bucket. """

    if not self.exists():
      if project_id is None:
        project_id = self._api.project_id
      try:
        self._info = self._api.buckets_insert(self._name, project_id=project_id)
      except Exception as e:
        raise e
    return self