Get Characters

 A program that returns every character used in a text file. It ignores if the letter is in uppercase or not. 

def characters():
    fo = open(input("Enter the name of your file: "), "r+")
    character_list = []
    character = "__"
    while character != "":
        character = fo.read(1)
        try:
            character = character.lower()
        except:
            pass
        if character not in character_list and character != "\n" and character != "":
            character_list.append(character)
    return character_list