class_docstr: source of buffered demonstration data 
class_docstr_tok: ["source","of","buffered","demonstration","data"]
docstr: start acquiring simulated data 
docstr_tok: ["start","acquiring","simulated","data"]
code: def start(self, timestamp):
      """start acquiring simulated data"""
      self.start_time = timestamp
      self.sample_idx = 0
  
file_path: pyqtgraph/pyqtgraph/examples/ColorGradientPlots.py
imports: import time
  import numpy
  import pyqtgraph
  from pyqtgraph.Qt import QtCore, mkQApp
label_desc: Use image node_id 2 for calling the DataSource obj's underlying member method code with example usage: obj.start(timestamp) without return types