docs: function getValidationsStack (validations, fields, data, messages, formatter) {
    return Object
      .keys(fields)
      .reduce((flatValidations, field) => {
        fields[field].map((rule) => {
          flatValidations.push(validationFn(validations, rule, field, data, messages, formatter))
        })
        return flatValidations
      }, [])
  }