Write a function named `contains`

that accepts two lists of integers *a1* and *a2* as parameters and that returns a value indicating whether or not *a2*'s sequence of elements appears in *a1* (`True`

for yes, `False`

for no).
The sequence of elements in *a2* may appear anywhere in *a1* but must appear consecutively and in the same order.
For example, if variables called `a1`

and `a2`

store the following values:

a1 = [1, 6, 2, 1, 4, 1, 2, 1, 8]
a2 = [1, 2, 1]

Then the call of `contains(a1, a2)`

should return `True`

because `a2`

's sequence of values `[1, 2, 1]`

is contained in `a1`

starting at index `5`

.
If `a2`

had stored the values `[2, 1, 2]`

, the call of `contains(a1, a2)`

would return `False`

because `a1`

does not contain that sequence of values.
Any two lists with identical elements are considered to contain each other, so a call such as `contains(a1, a1)`

should return `True`

.

You may assume that both lists passed to your function will have lengths of at least 1.
You may not use any strings to help you solve this problem, nor functions that produce strings such as `str`

.