code: def _valid_flex_int(s):
      """Returns True if s is a non-negative integer."""
      return isinstance(s, int) and s >= 0
  
imports: from random import shuffle
  import pytest
  import numpy
  import pennylane
  from pennylane.devices.qubit import simulate
  from pennylane.devices.qubit.simulate import _FlexShots
  from pennylane.devices.qubit import sample_state, measure_with_samples
  from pennylane.devices.qubit.sampling import _sample_state_jax
  from pennylane.measurements import Shots
label_desc: Use image node_id 2 for calling a global function with example usage: _valid_flex_int(s) and returns: unknown