code: def visit_IfExp(self, node):
          
          self.visit(node.test)
          body_res = self.visit(node.body)
          orelse_res = self.visit(node.orelse)
          return self.add(node, orelse_res.union(body_res))
docs: Use worst case for both possible values.
  
          >>> import gast as ast
          >>> from pythran import passmanager, backend
          >>> node = ast.parse('''
          ... def foo():
          ...     a = 2 or 3
          ...     b = 4 or 5
          ...     c = a if a else b''')
          >>> pm = passmanager.PassManager("test")
          >>> res = pm.gather(RangeValues, node)
          >>> res['c']
          Interval(low=2, high=5)