Integers between 1 and 3,999 (inclusive) are supported. Numbers beyond this
 range will return an OutOfRangeError.
 .
 The classical system of roman numerals requires that the same character may
 not appear more than thrice consecutively, meaning that 'MMMCMXCIX' (3,999)
 is the largest well-formed Roman numeral. The smallest is 'I' (1), as there
 is no symbol for zero in Roman numerals.
 .
 Both upper- and lower-case formatting of roman numerals are supported, and
 likewise for parsing strings, although the entire string must be of the same
 case. Numerals that do not adhere to the classical form are rejected with an
 InvalidRomanNumeralError.