code: def maximum_position(input, labels=None, index=None):
      """
      Find the positions of the maximums of the values of an array at labels.
  
      For each region specified by `labels`, the position of the maximum
      value of `input` within the region is returned.
  
      Parameters
      ----------
      input : array_like
          Array_like of values.
      labels : array_like, optional
          An array of integers marking different regions over which the
          position of the maximum value of `input` is to be computed.
          `labels` must have the same shape as `input`. If `labels` is not
          specified, the location of the first maximum over the whole
          array is returned.
  
          The `labels` argument only works when `index` is specified.
      index : array_like, optional
          A list of region labels that are taken into account for finding the
          location of the maxima.  If `index` is None, the first maximum
          over all elements where `labels` is non-zero is returned.
  
          The `index` argument only works when `labels` is specified.
  
      Returns
      -------
      output : list of tuples of ints
          List of tuples of ints that specify the location of maxima of
          `input` over the regions determined by `labels` and whose index
          is in `index`.
  
          If `index` or `labels` are not specified, a tuple of ints is
          returned specifying the location of the ``first`` maximal value
          of `input`.
  
      See also
      --------
      label, minimum, median, maximum_position, extrema, sum, mean, variance,
      standard_deviation
  
      """
      dims = numpy.array(numpy.asarray(input).shape)
      # see numpy.unravel_index to understand this line.
      dim_prod = numpy.cumprod([1] + list(dims[:0:-1]))[::-1]
  
      result = _select(input, labels, index, find_max_positions=True)[0]
  
      if numpy.isscalar(result):
          return tuple((result // dim_prod) % dims)
  
      return [
          tuple(v) for v in (result.reshape(-1, 1) // dim_prod) % dims
      ]
  
imports: from __future__ import division, print_function, absolute_import
  import numpy
  import numpy
  from .None import _ni_support
  from .None import _ni_label
  from .None import _nd_image
  from .None import morphology
label_desc: Use image node_id 15 for calling a global function with example usage: maximum_position(input, labels, index) and returns: unknown, tuple