Searching for the source of a method

In order to get a better idea of how the in_place_editor_field helper
works I searched the api docs and viewed the source of the method from
the api docs. I noticed that it calls in_place_editor which
instantiates ::ActionView::Helpers::InstanceTag. InstanceTag
unfortunately wasn’t documented in the apis anywhere so I had to go to
my ruby gems directory and search the text of all my ruby files to
find it. Is this typically how you would go about locating something
that isn’t documented? I miss just hitting F3 in eclipse for my Java

So after I located the class in form_helper.rb I wanted to figure out
what the value method does but I’m not sure how to go about locating
the source for the value method of self.class.value(object,
@method_name). Any ideas?