code: def lookup(parser, var, context, resolve=True, apply_filters=True):
      
      if resolve:
          try:
              return Variable(var).resolve(context)
          except VariableDoesNotExist:
              if apply_filters and var.find('|') > -1:
                  return parser.compile_filter(var).resolve(context)
              return Constant(var)
          except TypeError:
              # already resolved
              return var
      return var
docs: Try to resolve the varialbe in a context
      If ``resolve`` is ``False``, only string variables are returned