Hexadecimal constants start with a leading zero, followed by the letter ``x'' (either
upper or lower case). In addition to the decimal digits, these constants can
contain the letters `a`, `b`, `c`, `d`, `e`, or
`f` (again, either upper or lower case), representing the extra hexadecimal
digits beyond 9.

Note that these constants are numeric values, not string values, and thus should
not be surrounded by quotes. Trying to use a string representation of an
octal or hexadecimal constants raises a `TypeError` exception.

Arithmetic performed on octal or hexadecimal numbers will be displayed in
decimal form by the python interpreter. The functions `hex` and `oct`
convert their arguments into a string representation of the corresponding hexadecimal
or octal value, respectively.