Dict from list - HELP! PLEASE!

[cherry_cherry]

Unpack the list and check if the key value is already in the dictionary.

def check(seq):
    new_dict = {}
    for i in seq:
        (key, value), *rest = i.items()
        if value in new_dict:
            print("Numero en double! " + "---->" +
                  value + " Fichier non utilisable!")
        else:
            new_dict[value] = dict(rest)
    return new_dict

I don't know what you want to do for duplicated entries. The code above prints your message and excludes the duplicate entry.

If If the list has a number of key "numero" duplicated, it does not create a new dict. New dict is only available when all values of key "numero" are unique.