US President Donald Trump’s travel ban has caused a lot of trouble for those visiting the country. Among these was 28-year-old Celestine Omin, a software engineer travelling from Nigeria on business, who became the latest victim of the ban.

Omin disembarked at the John F. Kennedy Airport, New York, on Sunday. But before he could be allowed entry, he was asked to give a test proving he was a software engineer.

Omin works for Andela, a tech startup that connects developers in Africa with the employers in the United States. He was helping fintech startup First Access, based in New York, develop a JavaScript application for emerging markets. He had a short-term visa to visit the US.

According to a LinkedIn post that chronicles the incident, he waited for 20 minutes before being asked several questions concerning his profession by a Customs and Border Protection officer. Subsequently, he was taken to a small room and instructed to sit. After another hour passed, an officer came in and questioned him again.

Omin said the questions he was asked were done so in an accusatory tone. “Your visa says you are a software engineer. Is that correct?” he was asked. When Omin replied in the affirmative, he was handed a pen and a paper on which he was asked to answer a few questions – “Write a function to check if a Binary Search Tree is balanced” and “What is an abstract class, and why do you need it?”

Omin said he was “too tired to even think,” but he worked out the questions. However, after handing the paper back to the officer, he was told the responses to the questions were wrong. “No one would tell me why I was being questioned,” Omin said, according to the LinkedIn post. “Every single time I asked [the official] why he was asking me these questions, he hushed me … I wasn’t prepared for this. If I had known this was happening beforehand, I would have tried to prepare.”

Following the incident, he was sure he would not be allowed access into the United States. But an official told him he was free to go – adding that he wasn’t entirely convinced. “Look, I am going to let you go,” the official reportedly said. “But you don’t look convincing to me.” Omin was given the green signal to enter the country after the US Customs Office had called Andela and First Access to verify Omin’s occupation.

“Celestine was the first software engineer at one of the most visible e-commerce sites in Africa and is exactly the kind of person we want coming to America and sharing his skills,” Andela CEO Jeremy Johnson said. “Tapping into brilliant minds like Celestine’s is a huge help to many American companies who are struggling to find talent.”

Source: Ibtimes