According to LinkedIn, a Nigerian software engineer, Celestine Omin claims he was handed a written test by a US border officer at New York’s JFK airport to prove his tech credentials after a 24-hour flight from Lagos.

Mr Omin who is employed by tech start-up, Andela had been granted a short-term visa to work with First Access, a financial technology company in New York.

After landing, Omin was queried by a Customs and Border Protection officer. before being escorted  into a small room and told to sit down. Another hour passed before a different customs officer came in.

“Your visa says you are a software engineer. Is that correct?” an officer is reported to have asked Mr Omin.

He says he was then given a piece of paper and a pen and told to answer these two questions to prove he is actually a software engineer:

“Write a function to check if a Binary Search Tree is balanced.”

“What is an abstract class, and why do you need it?”

Mr Omin told LinkedIn it seemed to him the questions had been “Googled” by “someone with no technical background”.

He said later on Twitter that he was “too tired to even think”, and told the officer they could “talk about other computer science concepts”.

After he handed back his answers, he was told by the officer that they were wrong. He said he presumed he was required to provide “the Wikipedia definition” for the questions.