class_docstr: Augmenter that mask spectrogram based on frequency by random values.
  
  :param tuple zone: Default value is (0.2, 0.8). Assign a zone for augmentation. By default, no any augmentation
       will be applied in first 20% and last 20% of whole audio.
  :param float coverage: Default value is 1 and value should be between 0 and 1. Portion of augmentation. 
      If `1` is assigned, augment operation will be applied to target audio segment. For example, the audio 
      duration is 60 seconds while zone and coverage are (0.2, 0.8) and 0.7 respectively. 42 
      seconds ((0.8-0.2)*0.7*60) audio will be augmented.
  :param tuple factor: Default value is (40, 80) and value should not exceed number of mel frequency channels. 
      Factor value will be picked within the range of this tuple value. Mask range will be between 
      [0, v - factor) while v is the number of mel frequency channels.
  :param str name: Name of this augmenter
  
  >>> import nlpaug.augmenter.spectogram as nas
  >>> aug = nas.FrequencyMaskingAug()
code: def __init__(
      self,
      name="FrequencyMasking_Aug",
      zone=(0.2, 0.8),
      coverage=1.0,
      factor=(40, 80),
      verbose=0,
      silence=False,
      stateless=True,
  ):
      super().__init__(
          action=Action.SUBSTITUTE,
          zone=zone,
          coverage=coverage,
          factor=factor,
          verbose=verbose,
          name=name,
          silence=silence,
          stateless=stateless,
      )
  
      if self.factor[0] < 0 and not self.silence:
          Logger.log().warning(
              "Lower bound of factor is less than {}.".format(0)
              + " It should be non-negative value. Will use 0 as lower bound."
          )
  
      self.model = nms.FrequencyMasking()
  
file_path: nlpaug/nlpaug/augmenter/spectrogram/frequency_masking.py
imports: import numpy
  from nlpaug.augmenter.spectrogram import SpectrogramAugmenter
  from nlpaug.util import Action, Logger
  import nlpaug.model.spectrogram
label_desc: Use image node_id 1 to create a new FrequencyMaskingAug object from inherited base classes: SpectrogramAugmenter with example: obj = FrequencyMaskingAug(name, zone, coverage, factor, verbose, silence, stateless)