def gen_ascii_symbols(input_file, chars):
    """
    Return a dict of letters/numbers associated with
    the corresponding ascii-art representation.
    You can use http://www.network-science.de/ascii/ to generate the ascii-art for each symbol.
        
    The input file looks like:
    ,adPPYYba,  
    ""     `Y8  
    ,adPPPPP88  
    88,    ,88  
    `"8bbdP"Y8  
    88           
    88           
    88           
    88,dPPYba,   
    88P'    "8a  
    88       d8  
    88b,   ,a8"  
    8Y"Ybbd8"'
    
    ...
    
    Each symbol is separated by at least one empty line ("\n")
    """
    # input_file = 'ascii_symbols.txt'
    # chars = string.ascii_lowercase+string.ascii_uppercase+'0123456789'

    symbols = []
    s = ""
    with open(input_file, "r") as f:
        for line in f:
            if line == "\n":
                if len(s):
                    symbols.append(s)
                    s = ""
                else:
                    continue
            else:
                s += line

    return dict(zip(chars, symbols))