Use python

Create a function, encrypt()that prompts the user for a file name and read the textual content of the file and substitute the alphabetic characters in the message with the next character in the English alphabet, i.e., a becomes b, m becomes n. If there are z letters, substitute those with a. Leave non-alphabetic characters as is in the encrypted message. Then the function should print the encrypted message. Disregard the case of characters.