class_docstr: Generate data with matching histogram.
  
  :param embedding_matrix: The embedding matrix used to generator match
                           histogram.
  :param bin_size: The number of bin size of the histogram.
  :param hist_mode: The mode of the :class:`MatchingHistogramUnit`, one of
                   `CH`, `NH`, and `LCH`.
docstr: Init.
code: def __init__(
      self,
      embedding_matrix: np.ndarray,
      bin_size: int = 30,
      hist_mode: str = "CH",
  ):
      """Init."""
      self._match_hist_unit = mz.preprocessors.units.MatchingHistogram(
          bin_size=bin_size,
          embedding_matrix=embedding_matrix,
          normalize=True,
          mode=hist_mode,
      )
  
file_path: MatchZoo/matchzoo/data_generator/callbacks/histogram.py
imports: import numpy
  import matchzoo
  from matchzoo.data_generator.callbacks import Callback
label_desc: Use image node_id 1 to create a new Histogram object from inherited base classes: Callback with example: obj = Histogram(embedding_matrix, bin_size, hist_mode)