Can this shape be traced in a single line without lifting my pencil of the paper? Recently, a friend of mine gave me this challenge to trace this object in one line, without lifting a finger of the paper, and without tracing a line more than once, saying it was possible. 
P.S, the curvy squares at the end are actually ment to be semi-circles
Every time I try to do it myself, I always get so close with only one line left. I know this type of problems is generally solved using graph-theory (Not saying that this is necessarily solvable) , so any help is appreciated!

What you're wondering is if there is something called a Eulerian Path in this graph. An Eulerian Path is a sequence of edges in the graph, with consecutive edges incident in the graph, and this sequence of edges contains each edge of the graph exactly once. You can prove that a graph has an Eulerian path if it is connected and has at most two vertices of odd degree. If all the vertices are of even degree, then there actually exists an Eulerian circuit, a path that ends where it starts.
