How to change the deadline of the workitem programmatically in SAP?

Following code is used to changes the deadline of any work item which is in WAITING state. The FMs needs the input like the object type for which the workflow has executed, the workflow ID to which the workitem belongs and the Task id of the standard task which is executed and in waiting state.

DATA: lit_deadline TYPE TABLE OF swwdeadlin,
    lt_workitem TYPE TABLE OF swr_wihdr,
    lt_rel_wi TYPE TABLE OF swwwihead,
    w_workitem TYPE swr_wihdr,
    w_rel_wi TYPE swwwihead,
    w_deadline TYPE swwdeadlin,
    l_objkey TYPE swo_typeid,
    l_retcode TYPE sy-subrc.
* Retrieve the work items executed for desired Object type
CALL FUNCTION 'SAP_WAPI_WORKITEMS_TO_OBJECT'
  EXPORTING
    objtype                  = l_objtype
    objkey                   = l_objkey
    top_level_items          = space
    selection_status_variant = '0001'
  IMPORTING
    return_code              = l_ret_code
  TABLES
    worklist                 = lt_workitem.
* Select the workitems executed for particular Workflow.
SORT lt_workitem BY wi_rh_task wi_stat.
READ TABLE lt_workitem
     INTO w_workitem
     WITH KEY wi_rh_task = 'WS91001143'
              wi_stat = 'STARTED'
              BINARY SEARCH.
* Select the dependent workitems of 'WS91001143'.
  CALL FUNCTION 'SWI_GET_DEPENDENT_WORKITEMS'
    EXPORTING
      wi_id         = w_workitem-wi_id
    TABLES
      dependent_wis = lt_rel_wi.
*   Select the workitems for which the deadline needs to be changed.
  SORT lt_rel_wi BY wi_rh_task wi_stat.
  READ TABLE lt_rel_wi
       INTO w_rel_wi
       WITH KEY wi_rh_task = 'TS91001414'
                wi_stat = 'WAITING'
                BINARY SEARCH.
*   Update the deadline of the waiting task.
    w_deadline-wi_dattype = 'DS'.
    w_deadline-wi_date = l_new_date.
    w_deadline-wi_time = '000001'.
    APPEND w_deadline TO lt_deadline.
    CALL FUNCTION 'SWW_WI_DEADLINES_CHANGE'
      EXPORTING
        wi_id               = w_rel_wi-wi_id
        do_commit           = 'X'
      TABLES
        deadline_attributes = lt_deadline
      EXCEPTIONS
        no_authorization    = 1
        invalid_type        = 2
        update_failed       = 3
        invalid_status      = 4
        OTHERS              = 5.
if sy-subrc <> 0.

endif.