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 setValue(self, value):
      now = perf_counter()
      self.values.append((now, value))
      cutoff = now - self.averageTime
      while len(self.values) > 0 and self.values[0][0] < cutoff:
          self.values.pop(0)
      self.update()
  
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 2 for calling the ValueLabel obj's underlying member method code with example usage: obj.setValue(value) without return types