1..13
# ->clean()
 -  returns the numbers unmodified
 -  converts strings to numbers
 -  returns the numbers unmodified
 -  converts strings to numbers
 -  throws a sfValidatorError if the value is not a number
 -  returns null for null values
 -  checks the maximum number allowed
 -  option set the maximum number allowed
 -  error message customization
 -  checks the minimum number allowed
 -  option set the minimum number allowed
 -  throws a sfValidatorError
 -  error message customization
# Looks like everything went fine.