class_docstr: QLabel specifically for displaying numerical values.
  Extends QLabel adding some extra functionality:
  
    - displaying units with si prefix
    - built-in exponential averaging
code: def generateText(self):
      if len(self.values) == 0:
          return ""
      avg = self.averageValue()
      val = self.values[-1][1]
      if self.siPrefix:
          return fn.siFormat(avg, suffix=self.suffix)
      else:
          return self.formatStr.format(
              value=val, avgValue=avg, suffix=self.suffix
          )
  
file_path: pyqtgraph/pyqtgraph/widgets/ValueLabel.py
imports: from time import perf_counter
  from ..None import functions
  from ..Qt import QtWidgets
label_desc: Use image node_id 7 for calling the ValueLabel obj's underlying member method code with example usage: obj.generateText() and returns: str, fn, self