def self.export_proxy(scheme, path, user, pass)
path = "#{scheme}://#{path}" unless path.include?("://")
uri = Addressable::URI.encode(path, Addressable::URI)
if user && !user.empty?
userinfo = Addressable::URI.encode_component(user, USER)
if pass
userinfo << ":#{Addressable::URI.encode_component(pass, PASSWORD)}"
end
uri.userinfo = userinfo
end
path = uri.to_s
ENV["#{scheme}_proxy".downcase] = path unless ENV["#{scheme}_proxy".downcase]
ENV["#{scheme}_proxy".upcase] = path unless ENV["#{scheme}_proxy".upcase]
end