code: @CheckReturnValue
      public AuditableRestAction<Void> unban(User user)
      {
          Checks.notNull(user, "User");
  
          return unban(user.getId());
      }
docs: Unbans the specified {@link net.dv8tion.jda.core.entities.User User} from this Guild.
  
  <p>Possible {@link net.dv8tion.jda.core.requests.ErrorResponse ErrorResponses} caused by
  the returned {@link net.dv8tion.jda.core.requests.RestAction RestAction} include the following:
  <ul>
  <li>{@link net.dv8tion.jda.core.requests.ErrorResponse#MISSING_PERMISSIONS MISSING_PERMISSIONS}
  <br>The target Member cannot be unbanned due to a permission discrepancy</li>
  
  <li>{@link net.dv8tion.jda.core.requests.ErrorResponse#MISSING_ACCESS MISSING_ACCESS}
  <br>We were removed from the Guild before finishing the task</li>
  
  <li>{@link net.dv8tion.jda.core.requests.ErrorResponse#UNKNOWN_USER UNKNOWN_USER}
  <br>The specified User is invalid</li>
  </ul>
  
  @param  user
  The id of the {@link net.dv8tion.jda.core.entities.User User} to unban.
  
  @throws net.dv8tion.jda.core.exceptions.InsufficientPermissionException
  If the logged in account does not have the {@link net.dv8tion.jda.core.Permission#BAN_MEMBERS} permission.
  @throws IllegalArgumentException
  If the provided user is null
  
  @return {@link net.dv8tion.jda.core.requests.restaction.AuditableRestAction AuditableRestAction}