I'm trying to modify a gem which currently has a dependency on activeresource defined as: 

```
s.add_dependency              "activeresource", "~> 3.0"

```

In order to get the gem working with Rails 4, I need to extend the dependency to work with either version 3 or 4 of activeresource. I don't want to simply add the following as it could cause problems later:

```
s.add_dependency              "activeresource", ">= 3.0"

```

Is there a way to specify a list of acceptable versions? ~> 3.0 or ~> 4.0?