Matches() returns true if a value matches a regular expression.

MaxChars() returns true if a value contains no more than n characters.

MinChars() returns true if a value contains at least n characters.

NotBlank() returns true if a value is not an empty string.

Replace PermiteddInt() with a generic PermittedValue() function.

Use the regexp.MustCompile() function to parse a regular expression pattern for sanity checking the format of an email addres.

Define a new Validator type which contains a map of validation errors for our form fields.