How to show PL/SQL package output and fix below error(please help)

Question

--PACKAGE SPECIFICATION AND BODY complied successfully but I can not see output some error are also there..  please help ;how to fix this problem
-- with code
CREATE OR REPLACE PACKAGE package_variables IS
-- Declare package components.
PROCEDURE set(value VARCHAR2);
FUNCTION get RETURN VARCHAR2;
END package_variables;
CREATE OR REPLACE PACKAGE BODY package_variables IS
-- Declare package scope variable.
variable VARCHAR2(20) := 'Initial Value';
-- Define function
FUNCTION get RETURN VARCHAR2 IS
BEGIN
RETURN variable;
END get;
-- Define procedure.
PROCEDURE set(value VARCHAR2) IS
BEGIN
variable := value;
END set;
END package_variables;
VARIABLE outcome VARCHAR2(20)
CALL package_variables.get() INTO :outcome;
SELECT :outcome AS outcome FROM dual;
EXECUTE package_variables.set('New Value');
CALL package_variables.get() INTO :outcome;
SELECT :outcome AS outcome FROM dual;
OUTPUT
PACKAGE package_variables Compiled.
PACKAGE BODY package_variables Compiled.
Error starting at line 2 in command:
CALL package_variables.get() INTO :outcome
Error report:
SQL Error: ORA-01008: not all variables bound
01008. 00000 - "not all variables bound"
*Cause:   
*Action:
OUTCOME
1 rows selected
anonymous block completed
Error starting at line 2 in command:
CALL package_variables.get() INTO :outcome
Error report:
SQL Error: ORA-01008: not all variables bound
01008. 00000 - "not all variables bound"
*Cause:   
*Action:
OUTCOME
1 rows selected
*/

Answer 1

EXECUTE package_variables.set('New Value');
CALL package_variables.get INTO :outcome;
SELECT :outcome AS outcome FROM dual;
OUTPUT
anonymous block completed
Error starting at line 2 in command:
CALL package_variables.get INTO :outcome
Error report:
SQL Error: ORA-06576: not a valid function or procedure name
06576. 00000 - "not a valid function or procedure name"
*Cause:    Could not find a function (if an INTO clause was present) or
a procedure (if the statement did not have an INTO clause) to
call.
*Action:   Change the statement to invoke a function or procedure
OUTCOME
1 rows selected