code: def visit_Return(self, node):
          
          if not node.value:
              # Yielding function can't return values
              return
          for dep_set in self.visit(node.value):
              if dep_set:
                  for dep in dep_set:
                      self.result.add_edge(dep, self.current_function)
              else:
                  self.result.add_edge(TypeDependencies.NoDeps,
                                       self.current_function)
docs: Add edge from all possible callee to current function.
  
          Gather all the function call that led to the creation of the
          returned expression and add an edge to each of this function.
  
          When visiting an expression, one returns a list of frozensets. Each
          element of the list is linked to a possible path, each element of a
          frozenset is linked to a dependency.