Some help with Dictionaries

[Oshadha]

Script,

a_dic = {
    "a" :   [":D", ":)"],
    "b" :   ["lol", "XD"],
    "c" :   ["lol", ">:"],
    "d" :   [":)", "XD"]
}

How do I search for values and print out their key?

In a_dict i want to search ":)" and print its keys.

For example :

Search_item = ":)"

Output:
d
a