code: def add(self, username, user_api, filename=None):
          
          keys = API.__get_keys(filename)
          user = user_api.find(username)[0]
          distinguished_name = user.entry_dn
          if 'ldapPublicKey' not in user.objectClass:
              raise ldap3.core.exceptions.LDAPNoSuchAttributeResult(
                  'LDAP Public Key Object Class not found. ' +
                  'Please ensure user was created correctly.')
          else:
              for key in list(set(keys)):  # prevents duplicate insertion
                  print(key)
                  try:
                      SSHKey(key).parse()
                  except Exception as err:
                      raise err from None
                  else:
                      operation = {'sshPublicKey': [(ldap3.MODIFY_ADD, [key])]}
                      self.client.modify(distinguished_name, operation)
docs: Add SSH public key to a user's profile.
  
          Args:
              username: Username to attach SSH public key to
              filename: Filename containing keys to add (optional)
  
          Raises:
              ldap3.core.exceptions.LDAPNoSuchAttributeResult:
                  ldapPublicKey isn't attached to objectClass