code: function parseBlending (blending) {
    switch (blending) {
      case 'none': {
        return THREE.NoBlending;
      }
      case 'additive': {
        return THREE.AdditiveBlending;
      }
      case 'subtractive': {
        return THREE.SubtractiveBlending;
      }
      case 'multiply': {
        return THREE.MultiplyBlending;
      }
      default: {
        return THREE.NormalBlending;
      }
    }
  }
docs: Return a three.js constant determining blending
  
  @param {string} [blending=normal]
  - `none`, additive`, `subtractive`,`multiply` or `normal`.
  @returns {number}