Get item from the table.

def get_item(cls, hash_key, range_key=None):
        """ Get item from the table."""
        key = cls._encode_key(hash_key, range_key)
        raw_data = cls._get_connection().get_item(cls.get_table_name(), key)
        if 'Item' not in raw_data:
            raise ItemNotFoundException
        return cls.from_raw_data(raw_data['Item'])