code: function validatorDropDown(fieldValue, fieldDefinition, previousFieldValues, cb) {
        if (typeof(fieldValue) !== "string") {
          return cb(new Error("Expected submission to be string but got " + typeof(fieldValue)));
        }
  
        fieldDefinition.fieldOptions = fieldDefinition.fieldOptions || {};
        fieldDefinition.fieldOptions.definition = fieldDefinition.fieldOptions.definition || {};
  
        //Check values exists in the field definition
        if (!fieldDefinition.fieldOptions.definition.options) {
          return cb(new Error("No options exist for field " + fieldDefinition.name));
        }
  
        //Finding the selected option
        var found = _.find(fieldDefinition.fieldOptions.definition.options, function(dropdownOption) {
          //check if fieldValue and the label need to be escaped
          isSafeString(fieldValue) ? null : fieldValue = _.escape(fieldValue);
          isSafeString(dropdownOption.label) ? null : dropdownOption.label = _.escape(dropdownOption.label);
          return dropdownOption.label === fieldValue;
        });
  
        //Valid option, can return
        if (found) {
          return cb();
        }
  
        //If the option is empty and the field is required, then the blank option is being submitted
        //The blank option is not valid for a required field.
        if (found === "" && fieldDefinition.required && fieldDefinition.fieldOptions.definition.include_blank_option) {
          return cb(new Error("The Blank Option is not valid. Please select a value."));
        } else {
          //Otherwise, it is an invalid option
          return cb(new Error("Invalid option specified: " + fieldValue));
        }
      }
docs: validatorDropDown - Validator function for dropdown fields.
  
  @param  {string} fieldValue        The value to validate
  @param  {object} fieldDefinition   Full JSON definition of the field
  @param  {array} previousFieldValues Any values previously stored with the fields
  @param  {function} cb               Callback function