lib/classes/Variables.js/Variables/populateService
class Variables:  populateService(processedOptions) {
    const that = this;
    this.options = processedOptions || {};

    this.loadVariableSyntax();

    const variableSyntaxProperty = this.service.defaults.variableSyntax;

    // temporally remove variable syntax from service otherwise it'll match
    this.service.defaults.variableSyntax = true;

    /*
     * we can't use an arrow function in this case cause that would
     * change the lexical scoping required by the traverse module
     */
    traverse(this.service).forEach(function (propertyParam) {
      const t = this;
      let property = propertyParam;

      if (typeof property === 'string') {
        property = that.populateProperty(property);
        t.update(property);
      }
    });

    this.service.defaults.variableSyntax = variableSyntaxProperty;
    return this.service;
  }