[Feature request] `indefinitize` to get the correct indefinite article?

[redsun82]

It would be nice to have a indefinitize function to add the correct indefinite article:

indefinitize("child") == "a child"
indefinitize("element") == "an element"
indefinitize("universe") == "a universe"
indefinitize("undisclosed recipient") == "an undisclosed recipient"

The rules only gets a bit more complicated when dealing with "u" as first letter.