Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_2155836_1 (population__millions VARCHAR, _2011_ VARCHAR, gdp__nominal___billions_usd_ VARCHAR)
### Question:
What is the population in millions for 2011 where the GDP (nominal) (billions USD) is 4? 
### Answer:
SELECT population__millions, _2011_ FROM table_2155836_1 WHERE gdp__nominal___billions_usd_ = "4"