Question: When using the interpreter, the expression `'a' in ('abc')` returns True, while `'a' in ['abc']` returns False. Can somebody explain this behaviour?

Answer: 
As others has mentioned, `('abc')` is not a tuple. `'a'` is not a element of `['abc']`. The only element in that list is `'abc'`

```
x='abc' in ['abc']

print (x)

True #This will evaluate to true

```

This will also evaluate to true:

```
y = 'a' in ['a','b','c']

print (y)

True

```
`('abc')` is equivalent to `'abc'`.

`'a' in ('abc')` is equivalent to `'a' in 'abc'`.

`'a' in ('abc', )` returns `False` as `'a' in ['abc']`.

`'a' in ['a', 'b', 'c']` returns `True` as `'a' in 'abc'`.