old_contents: from flask import Request, Response
  class RqRequest(Request):
      def rq_headers(self):
          headers = {}
          if 'Authorization' in self.headers:
              headers['Authorization'] = self.headers['Authorization']
          if self.headers['Accept'] == 'application/xml':
              headers['Accept'] = 'application/xml'
          else:
              headers['Accept'] = 'application/json'
          return self.headers
  
      # request.form is a Werkzeug MultiDict
      # we want to create a string
      def rq_data(self):
          data = ""
          for k, v in self.form.iteritems():
              data += k + "=" + v + "&"
          return data
  
      def rq_params(self):
          return self.args.to_dict()
  
  
new_contents: from flask import Request, Response
  class RqRequest(Request):
      def rq_headers(self):
          headers = {}
          if 'Authorization' in self.headers:
              headers['Authorization'] = self.headers['Authorization']
          if self.headers.get('Accept') == 'application/xml':
              headers['Accept'] = 'application/xml'
          else:
              headers['Accept'] = 'application/json'
          return self.headers
  
      # request.form is a Werkzeug MultiDict
      # we want to create a string
      def rq_data(self):
          data = ""
          for k, v in self.form.iteritems():
              data += k + "=" + v + "&"
          return data
  
      def rq_params(self):
          return self.args.to_dict()
  
  
subject: Fix KeyError when accessing non-existing header