code: def set_number_of_annotation_signals(self, number_of_annotations):
          
          number_of_annotations = max((min((int(number_of_annotations), 64)), 1))
          self.number_of_annotations = number_of_annotations
          self.update_header()
docs: Sets the number of annotation signals. The default value is 1
          This function is optional and can be called only after opening a file in writemode
          and before the first sample write action
          Normally you don't need to change the default value. Only when the number of annotations
          you want to write is more than the number of seconds of the duration of the recording, you can use
          this function to increase the storage space for annotations
          Minimum is 1, maximum is 64
  
          Parameters
          ----------
          number_of_annotations : integer
              Sets the number of annotation signals