code: function preferences_setPref(prefName, value, interfaceType) {
      try {
        switch (typeof value) {
          case ('boolean'):
            this.prefBranch.setBoolPref(prefName, value);
            break;
          case ('string'):
            this.prefBranch.setCharPref(prefName, value);
            break;
          case ('number'):
            this.prefBranch.setIntPref(prefName, value);
            break;
          default:
            this.prefBranch.setComplexValue(prefName, interfaceType, value);
        }
      } catch(e) {
        return false;
      }
  
      return true;
    }
docs: Set the value of an individual preference.
  
  @param {string} prefName
  The preference to set the value of.
  @param {boolean/number/string/complex} value
  The value to set the preference to.
  @param {string} interfaceType
  Interface to use for the complex value
  (nsILocalFile, nsISupportsString, nsIPrefLocalizedString)
  
  @return Returns if the value was successfully set.
  @type boolean