code: def standard_deviation(input, labels=None, index=None):
      """Calculates the standard deviation of the values of an n-D image array,
      optionally at specified sub-regions.
  
      Args:
          input (cupy.ndarray): Nd-image data to process.
          labels (cupy.ndarray or None): Labels defining sub-regions in `input`.
              If not None, must be same shape as `input`.
          index (cupy.ndarray or None): `labels` to include in output. If None
              (default), all values where `labels` is non-zero are used.
  
      Returns:
          standard_deviation (cupy.ndarray): standard deviation of values, for
          each sub-region if `labels` and `index` are specified.
  
      .. seealso:: :func:`scipy.ndimage.standard_deviation`
      """
      return cupy.sqrt(variance(input, labels, index))
  
imports: import warnings
  import numpy
  import cupy
  from cupy import _core
  from cupy import _util
label_desc: Use image node_id 16 for calling a global function with example usage: standard_deviation(input, labels, index) and returns: cupy