Strings

import string


def strings(filename, min_str_len=4):
    set_of_symbols = set([ord(i) for i in string.printable])
    with open(filename, 'rb') as file:
        for str in file:
            result = ''
            for sym in str:
                if sym in set_of_symbols:
                    result += chr(sym)
                else:
                    if len(result) > min_str_len:
                        yield result
                    result = ''
            if len(result) > min_str_len:
                yield result