Convert a character to the integer it denotes. ‘0’ through ‘9’ convert to 0 to 9, and ‘a’ through ‘z’ convert to 10 to 35. An error is signaled if the character is not in this range.
sealed
| character | An instance of <character>. An error is signaled if it is not alphanumeric. |
| integer | An instance of <integer> between 0 and 35 inclusive. |