The text of the code description specifies, "Technically, a code is restricted to a string which has at least one character and no leading or trailing whitespace, and where there is no whitespace other than single spaces in the contents".  One of the usages of the `\s` metacharacter in the current regex is incorrect because it allows characters other than space, e.g., tab, carriage return, newline, etc..  I believe the correct regex to be as follows: 

[^\s]+( [^\s]+)*