code: def update_user(self, user_id,
                      roles=None, netmask=None,
                      secret=None, pubkey=None):
          
          arguments = {'roles': roles,
                       'netmask': netmask,
                       'secret': secret,
                       'pubkey': pubkey}
          return self.do_req('PUT',
                             self.merchant_api_base_url + '/user/' +
                             user_id + '/', arguments)
docs: Update user. Returns the raw response object.
  
          Arguments:
              user_id:
                  User id of user to update
              roles:
                  Role
              netmask:
                  Limit user connections by netmask, for example 192.168.1.0/24
              secret:
                  Secret used when authenticating with mCASH
              pubkey:
                  RSA key used for authenticating by signing