code: function getTimeFunction(audioContext = null) {
    if (isNode()) {
      return () => {
        const t = process.hrtime();
        return t[0] + t[1] * 1e-9;
      }
    } else {
      return () => performance.now() / 1000;
    }
  }
docs: Create a function that returns time in seconds according to the current
  environnement (node or browser).
  If running in node the time rely on `process.hrtime`, while if in the browser
  it is provided by the `currentTime` of an `AudioContext`, this context can
  optionnaly be provided to keep time consistency between several `EventIn`
  nodes.
  
  @param {AudioContext} [audioContext=null] - Optionnal audio context.
  @return {Function}
  @private