class_docstr: Create a tempo histogram with autocorrelation.
  
  Parameters
  ----------
  min_bpm : float, optional
      Minimum tempo to detect [bpm].
  max_bpm : float, optional
      Maximum tempo to detect [bpm].
  hist_buffer : float
      Aggregate the tempo histogram over `hist_buffer` seconds.
  fps : float, optional
      Frames per second.
  online : bool, optional
      Operate in online (i.e. causal) mode.
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docstr: Compute the histogram of the beat intervals with the autocorrelation
  function.
  
  Parameters
  ----------
  activations : numpy array
      Beat activation function.
  
  Returns
  -------
  histogram_bins : numpy array
      Bins of the beat interval histogram.
  histogram_delays : numpy array
      Corresponding delays [frames].
code: def process_offline(self, activations, **kwargs):
      """
      Compute the histogram of the beat intervals with the autocorrelation
      function.
  
      Parameters
      ----------
      activations : numpy array
          Beat activation function.
  
      Returns
      -------
      histogram_bins : numpy array
          Bins of the beat interval histogram.
      histogram_delays : numpy array
          Corresponding delays [frames].
  
      """
      # build the tempo (i.e. inter beat interval) histogram and return it
      return interval_histogram_acf(
          activations, self.min_interval, self.max_interval
      )
  
imports: from __future__ import absolute_import, division, print_function
  import sys
  import warnings
  from operator import itemgetter
  import numpy
  from ..audio.signal import smooth
  from ..processors import BufferProcessor, OnlineProcessor
label_desc: Use image node_id 3 for calling the ACFTempoHistogramProcessor obj's underlying member method code with example usage: obj.process_offline(activations) and returns: interval_histogram_acf