code: def set_context_params(self, params):
  
          
  
          for key, value in params.items():
  
              if key not in self.valid_context_params:
  
                  raise RequestHeaderContextException(
                      "%s is not a valid context parameter." % key
                  )
docs: Set header context parameters. Refer to the top of <Zimbra
          Server-Root>/docs/soap.txt about specifics.
  
          The <format>-Parameter cannot be changed, because it is set by the
          implementing class.
  
          Should be called by implementing method to check for valid context
          params.
  
          :param params: A Dict containing context parameters.