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![Jordon Crichton](https://secure.gravatar.com/avatar/00402c467d69e3e6b696c32e8d44665d?s=96&d=https%3A%2F%2Fecs-static.teamtreehouse.com%2Fassets%2Fcontent%2Fdefault_avatar-445fbbabfc8dc9188fb5967fe43322ee0c3e0dd1e10f378bf8343784af5a13eb.webp&r=pg)
Jordon Crichton
1,868 PointsI wrote code that works in the console but produces an error in the challenge saying " Not the right output"
write a function named covers that accepts a single parameter, a set of topics. Have the function return a list of courses from COURSES where the supplied set and the course's value (also a set) overlap.
For example, covers({"Python"}) would return ["Python Basics"].
COURSES = {
"Python Basics": {"Python", "functions", "variables",
"booleans", "integers", "floats",
"arrays", "strings", "exceptions",
"conditions", "input", "loops"},
"Java Basics": {"Java", "strings", "variables",
"input", "exceptions", "integers",
"booleans", "loops"},
"PHP Basics": {"PHP", "variables", "conditions",
"integers", "floats", "strings",
"booleans", "HTML"},
"Ruby Basics": {"Ruby", "strings", "floats",
"integers", "conditions",
"functions", "input"}
}
def covers(set):
course_cover=[]
for cover in COURSES.keys():
if set & COURSES[cover] == set:
course_cover.append(cover)
return course_cover
2 Answers
![Steven Parker](https://uploads.teamtreehouse.com/production/profile-photos/969492/micro_tool_chess_set_2.jpg)
Steven Parker
230,688 PointsYour test is a bit too specific. The union (&) by itself will detect an overlap, but by comparing that result to the original argument, you are further restricting it to a subset. That's not quite what the challenge is asking for in this task.
Bonus hint: You might keep it in mind for the next task.
![Jordon Crichton](https://secure.gravatar.com/avatar/00402c467d69e3e6b696c32e8d44665d?s=96&d=https%3A%2F%2Fecs-static.teamtreehouse.com%2Fassets%2Fcontent%2Fdefault_avatar-445fbbabfc8dc9188fb5967fe43322ee0c3e0dd1e10f378bf8343784af5a13eb.webp&r=pg)
Jordon Crichton
1,868 PointsI fixed it with len(set & COURSES[cover]) == 0 then continue else append the cover. However, is there another way to use a null set in an argument.
![Steven Parker](https://uploads.teamtreehouse.com/production/profile-photos/969492/micro_tool_chess_set_2.jpg)
Steven Parker
230,688 PointsYou could have just left off the equality comparison and used "set & COURSES[cover]
" as the whole expression. When the result is empty, it's considered "falsey" by Python, and if it contains anything it is "truthy".