シーザー暗号のPython実装です：

``` python
def caesar_cipher_encrypt(plain_text, shift):
    """
    Encrypts the given plaintext using the Caesar Cipher algorithm with the given shift value.
    
    :param plain_text: the plaintext to be encrypted
    :param shift: the shift value used for encryption
    :return: the encrypted ciphertext
    """
    cipher_text = ""
    for char in plain_text:
        if char.isalpha():
            # Get the ASCII value of the character
            ascii_val = ord(char)
            
            # Determine whether the character is uppercase or lowercase
            if char.isupper():
                # Shift the ASCII value by the specified number of positions and wrap around if necessary
                shifted_ascii_val = ((ascii_val - 65 + shift) % 26) + 65
                
            else:
                shifted_ascii_val = ((ascii_val - 97 + shift) % 26) + 97
                
            # Convert the shifted ASCII value back to a character and add it to the ciphertext
            cipher_text += chr(shifted_ascii_val)
        else:
            # Add non-alphabetic characters to the ciphertext unchanged
            cipher_text += char
            
    return cipher_text
```

この関数は2つのパラメータを受け取ります：暗号化される平文と、暗号化に使われるシフト値です。次に、この関数は平文の各文字をループし、それがアルファベット文字であるかどうかをチェックします。アルファベットである場合、関数はその文字が大文字か小文字かを判別し、その文字の ASCII 値を指定された位置だけシフトし、必要に応じて折り返し、シフトされた ASCII 値を文字に変換します。文字がアルファベットでない場合、その文字は変更されずに暗号文に追加される。そして暗号化された暗号文が返される。
Here is a Python implementation of the Caesar Cipher encryption algorithm:

``` python
def caesar_cipher_encrypt(plain_text, shift):
    """
    Encrypts the given plaintext using the Caesar Cipher algorithm with the given shift value.
    
    :param plain_text: the plaintext to be encrypted
    :param shift: the shift value used for encryption
    :return: the encrypted ciphertext
    """
    cipher_text = ""
    for char in plain_text:
        if char.isalpha():
            # Get the ASCII value of the character
            ascii_val = ord(char)
            
            # Determine whether the character is uppercase or lowercase
            if char.isupper():
                # Shift the ASCII value by the specified number of positions and wrap around if necessary
                shifted_ascii_val = ((ascii_val - 65 + shift) % 26) + 65
                
            else:
                shifted_ascii_val = ((ascii_val - 97 + shift) % 26) + 97
                
            # Convert the shifted ASCII value back to a character and add it to the ciphertext
            cipher_text += chr(shifted_ascii_val)
        else:
            # Add non-alphabetic characters to the ciphertext unchanged
            cipher_text += char
            
    return cipher_text
```

This function takes in two parameters: the plaintext to be encrypted, and the shift value used for encryption. The function then loops over each character in the plaintext, checking whether it is an alphabetic character. If it is, the function determines whether it is uppercase or lowercase, shifts the ASCII value of the character by the specified number of positions, wraps around if necessary, and converts the shifted ASCII value back to a character. If the character is not alphabetic, it is added to the ciphertext unchanged. The encrypted ciphertext is then returned.