def find(chambre, etiquette):
    """Find all occurence of etiquette in chambre and return a list of all his position

    :chambre: matrice of item in chambre
    :etiquette: Element to find in chambre as string
    :returns: list of positions

    """
    ret = list()
    for x in range(len(chambre)):
        for y in range(len(chambre[x])):
            if etiquette == chambre[x][y]:
                ret.append((x,y))
    return ret

# Tests
if __name__ == "__main__":
    chambre = [
            [ "A" , "A" , "B" , "D"  ],
            [ "C" , "P" , "U" , "A"  ],
            [ "M" , "O" , "N" , "S " ],
            [ "A" , "B" , "D" , "A"  ]
             ]
    print(find(chambre, 'A'), "should print 5 elemets")
    print(find(chambre, 'C'), "Should print 1 element")
    print(find(chambre, 'Elephant'), "Should print nothing")