The first one that never repeats

Problem

Write a function that takes a text and returns the first character that never repeats, that is, the one that shows up a single time in the whole text.

In bubble the answer is u: the b shows up three times, so it does not count, and the u shows up only once.

Watch out for one trap: it is not the first character you had not seen before, it is the one that shows up nowhere else in the text, neither before nor after. In ababc the answer is c, because the a and the b come back later on.

If no character fits, you return the empty text "". With an empty text you also return "".

A space counts as one more character.

Hint: for each character you can walk the whole text counting how many times it shows up. The first one that shows up a single time is the answer.

Examples

• Skips the one that repeats

  "bubble" → "u"

• The first one already works

  "melon" → "m"

• All the way to the last letter

  "ababc" → "c"

• A single letter

  "z" → "z"

Besides these, the challenge has hidden tests that are revealed when you submit your solution.

You start with this

def first_unique(text):
    pass

function firstUnique(text) {
}