You have the documentation in the source of http.rb
M> resp, data = h.get('/index.html', nil )
M> net/http: warning: old style assignment found at ./test.rb:6
# Gets data from +path+ on the connected-to host.
# +header+ must be a Hash like { 'Accept' => '*/*', ... }.
#
# In version 1.1 (ruby 1.6), this method returns a pair of objects,
# a Net::HTTPResponse object and the entity body string.
# In version 1.2 (ruby 1.8), this method returns a Net::HTTPResponse
# object.
#
# If called with a block, yields each fragment of the
# entity body in turn as a string as it is read from
# the socket. Note that in this case, the returned response
# object will *not* contain a (meaningful) body.
#
# +dest+ argument is obsolete.
# It still works but you must not use it.
#
# In version 1.1, this method might raise an exception for
# 3xx (redirect). In this case you can get a HTTPResponse object
# by "anException.response".
#
# In version 1.2, this method never raises exception.
#
# # version 1.1 (bundled with Ruby 1.6)
# response, body = http.get('/index.html')
#
# # version 1.2 (bundled with Ruby 1.8 or later)
# response = http.get('/index.html')
#
# # using block
# File.open('result.txt', 'w') {|f|
# http.get('/~foo/') do |str|
# f.write str
# end
# }
#
1.1 is the old style