code: function ControlComposer(opts) {
    opts = opts || {};
  
    this._methods = [];
  
    this._parameters = [ 'x' ,'y', 'axisScaledX', 'axisScaledY', 'zoom', 'yaw', 'pitch', 'roll' ];
  
    this._now = opts.nowForTesting || now;
  
    this._composedOffsets = { };
  
    this._composeReturn = { offsets: this._composedOffsets, changing: null };
  }
docs: @class ControlComposer
  @classdesc
  
  Combines changes in parameters triggered by multiple {@link ControlMethod}
  instances.
  
  @listens ControlMethod#parameterDynamics