list and tuple have an index-method to get the position of the element:
alist = [10, 16, 26, 5, 2, 19, 105, 26]
# search for 16 in the list
alist.index(16) # 1
alist[1] # 16
alist.index(15)
ValueError: 15 is not in list
But only returns the position of the first found element:
...