# File lib/oauth/signature.rb, line 7
    def self.build(request, options = {}, &block)
      request = OAuth::RequestProxy.proxy(request, options)
      klass = available_methods[(request.signature_method || "").downcase]
      raise UnknownSignatureMethod, request.signature_method unless klass
      klass.new(request, options, &block)
    end