code: def visit_Assign(self, node):
          
          assigned_range = self.visit(node.value)
          for target in node.targets:
              if isinstance(target, ast.Name):
                  # Make sure all Interval doesn't alias for multiple variables.
                  self.add(target.id, assigned_range)
              else:
                  self.visit(target)
docs: Set range value for assigned variable.
  
          We do not handle container values.
  
          >>> import gast as ast
          >>> from pythran import passmanager, backend
          >>> node = ast.parse("def foo(): a = b = 2")
          >>> pm = passmanager.PassManager("test")
          >>> res = pm.gather(RangeValues, node)
          >>> res['a']
          Interval(low=2, high=2)
          >>> res['b']
          Interval(low=2, high=2)