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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 summary(self):
 """Summary string of mean and standard deviation. Returns: Summary tensor. """

    with tf.name_scope(self._name + '/summary'):
      mean_summary = tf.cond(
          self._count > 0, lambda: self._summary('mean', self._mean), str)
      std_summary = tf.cond(
          self._count > 1, lambda: self._summary('stddev', self._std()), str)
      return tf.summary.merge([mean_summary, std_summary])