code: function buildPreviewUrl (pose, scale, gender, style, rotation, traits, outfit) {
  
    // use string templating to build the url
    let url = `${basePreviewUrl}${pose}?scale=${scale}&gender=${gender}&style=${style}`
    url += `&rotation=${rotation}${mapTraits(traits).join("")}&outfit=${outfit}`
    return url;
  }
docs: returns the image url of a bitmoji avatar with the specified parameters