'Return a string containing the *char_count* bytes at the file
position determined by self._base_offset + *base* + *offset*.'

def read_str(self, char_count, base, offset=0):

    def str_struct(char_count):
        format_ = ('%ds' % char_count)
        return Struct(format_)
    struct = str_struct(char_count)
    chars = self._unpack_item(struct, base, offset)
    unicode_str = chars.decode('UTF-8')
    return unicode_str
