docs: def _prep_binary_mimetype(self):
  
  		'''
  		Sets Content-Type header based on headers and/or self.binary.mimetype values
  		Implicitly favors Content-Type header if set
  
  		Args:
  			None
  
  		Returns:
  			None: sets attributes in self.binary and headers
  		'''
  
  		# neither present
  		if not self.mimetype and 'Content-Type' not in self.resource.headers.keys():
  			raise Exception('to create/update NonRDFSource, mimetype or Content-Type header is required')
  
  		# mimetype, no Content-Type
  		elif self.mimetype and 'Content-Type' not in self.resource.headers.keys():
  			logger.debug('setting Content-Type header with provided mimetype: %s'
  				% self.mimetype)
  			self.resource.headers['Content-Type'] = self.mimetype