Case Sensitivity in Python

lower upper swapcase capitalize casefold title

Given a string:

Make all the letters in it lowercase.

Given a string:

Capitalize all letters in this line.

Given a string:

Capitalize the first letter of this line.

Given a string:

Capitalize the first letter of each word in this line:

Given a string:

Change the case of the characters to the opposite:

Given a list:

Let each of its elements begin with a capital letter.

Suppose you have a dictionary where the keys are usernames and the values ​​are their emails. Write code so that all the letters in the email strings are lowercase.