code: def add_subject(self, subject_id, attributes, parents=[],
              issuer='default'):
          
          # MAINT: consider test to avoid adding duplicate subject id
          assert isinstance(attributes, (dict)), "attributes expected to be dict"
  
          attrs = []
          for key in attributes.keys():
              attrs.append({
                  'issuer': issuer,
                  'name': key,
                  'value': attributes[key]
                  })
  
          body = {
              "subjectIdentifier": subject_id,
              "parents": parents,
              "attributes": attrs,
          }
  
          return self._put_subject(subject_id, body)
docs: Will add the given subject with a given identifier and attribute
          dictionary.
  
              example/
  
                  add_subject('/user/j12y', {'username': 'j12y'})