Ceaser Cipher in Python

Ceaser Cipher in Python

"""
Implement Caesar’s cipher: implement a function encrypt that 
given a plaintext string and a key  𝑘  (how many letters to shift), 
returns a ciphertext where each character is shifted  𝑘  places.
(You can assume all characters are lowercase letters, with no punctuation or spaces.)
"""

alphabet = 'abcdefghijklmnopqrstuvwxyz'

def encrypt(plaintext="hithere", k=4):
    ciphertext = ""
    for letter in plaintext:
        letterLocation = 0
        for alpLetter in alphabet:
            if (letter == alpLetter):
                break
            letterLocation += 1
            
        cipherLetter = alphabet[letterLocation - k]
        ciphertext = ciphertext + cipherLetter
    return ciphertext

print( encrypt() )
#encrypt()

# the fastest may to get the location of the letter in the string
# alpLetterLocation = alphabet.index(letter) + k
# encrypted_data += alphabet[alpLetterLocation]