'''
For this exercise, you can use the following documentation:
https://docs.python.org/3/tutorial/datastructures.html#more-on-lists.

# Lists

A sequence is a data structure that contains items arranged in order, and you 
can access each item using an integer index that represents its position in 
the sequence. You have already encountered strings as an example of a sequence.

Lists allow you to store multiple items in a single variable. They have a 
defined order, which allows you to retrieve items based on their position in 
the list. Contrary to tuples however, lists are mutable, which means you can 
easy change, add, or remove items.

In this exercise, we'll explore the usefulness of lists by looking at a list 
containing all 20 naturally occurring amino acids:
'''

amino_acids = [
    "Methionine", "Histidine", "Threonine", "Arginine", "Alanine",
    "Glycine", "Tyrosine", "Proline", "Asparagine", "Valine",
    "Phenylalanine", "Leucine", "Glutamine", "Cysteine", "Aspartic acid",
    "Isoleucine", "Serine", "Tryptophan", "Lysine", "Glutamic acid"
]

'''
First, sort this list alphabetically using built-in function `sorted()`.
'''

amino_acids = # Add your code here

'''
Now, determine the index of Glutamine (hint: see the documentation) and use 
that to retrieve it from the list:
'''

index_glutamine =
glutamine = amino_acids[..]
print(glutamine)

'''
Define a list of all amino acids starting with an A by using slicing, 
i.e. indexing of multiple items. You can slice multiple items as follows: 
`list_name[start:stop]` - the item with index start will be included, 
whereas the item with index stop will not be included.
'''

amino_acids_starting_with_an_A =
print(amino_acids_starting_with_an_A)

'''
Add the amino acid "Selenocysteine", the Se-analogue of cysteine, to the list. 
Make sure that your final list is again sorted alphabetically!
'''

# Your code here

'''
You can check whether a specific item is in a list using a Boolean variable. 
Use `input()` and the Boolean variable `is_this_an_amino_acid` to check 
whether your input string is in the extended list of amino acids.
'''

your_amino_acid = input() # Make sure that this variable is of the correct type
is_this_an_amino_acid = .. in ..
print(f"{your_amino_acid} is an amino acid: {is_this_an_amino_acid}")