class_docstr: Normal Distribution.
  
  The probability density function of the distribution is expressed as
  
  .. math::
      p(x;\mu,\sigma) = \frac{1}{\sqrt{2\pi\sigma^2}}
          \exp\left(-\frac{(x-\mu)^2}{2\sigma^2}\right)
  
  Args:
      loc(:class:`~chainer.Variable` or :ref:`ndarray`): Parameter of
          distribution representing the location :math:`\mu`. This is the
          mean parameter.
      scale(:class:`~chainer.Variable` or :ref:`ndarray`): Parameter of
          distribution representing the scale :math:`\sigma`. Either `scale`
          or `log_scale` (not both) must have a value.
      log_scale(:class:`~chainer.Variable` or :ref:`ndarray`): Parameter of
          distribution representing the scale :math:`\log(\sigma)`. Either
          `scale` or `log_scale` (not both) must have a value.
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code: def stddev(self):
      return self.scale
  
imports: import math
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import distribution
  from chainer.functions.math import exponential
  from chainer.functions.math import log_ndtr
  from chainer.functions.math import ndtr
  from chainer.functions.math import ndtri
  from chainer.utils import argument
  from chainer.utils import cache
  import chainerx
label_desc: Use image node_id 17 for calling the Normal obj's underlying member method code with example usage: obj.stddev() and returns: self