human
Solve the following python programming problem given the following code:
def FindSourceFiles(self, node = '.') : 
    ' returns a list of all source files.
        ' 
    node = self.arg2nodes (node, self.fs.Entry) [0] 
    sources = [] 
    def build_source(ss) : 
        for s in ss : 
            if isinstance (s, SCons.Node.FS.Dir) : 
                build_source (s.all_children ()) 
else : 
                if s.has_builder () : 
                    build_source (s.sources) 
else : 
                    if isinstance (s.disambiguate (), SCons.Node.FS.File) : 
                        sources.append (s) 
build_source (node.all_children ()) 
    def final_source(node) : 
        while (node != node.srcnode ()) : 
            node = node.srcnode () 
return node 
sources = map (final_source, sources) 
    return list (set (self)) 

    
    

    Fix the buggy line: return list (set (self))
assistant
#Here is Python program to fix the buggy line: return list (set (self))
.

return list (set (sources))