code: func (v *Validator) Equal(field1 string, field2 string) *ValidationResult {
  	val1 := v.data.Get(field1)
  	val2 := v.data.Get(field2)
  	if val1 != val2 {
  		return v.addEqualError(field1, field2)
  	} else {
  		return validationOk
  	}
  }
docs: // Equal will add an error to the Validator if data[field1]
  // is not equal to data[field2].