Write a subroutine TO_UPPER, using either pseudo-code or a flowchart, that takes a single lowercase character as a parameter and returns the corresponding uppercase character.

For example, if the subroutine TO_UPPER is passed the character 'e' as a parameter, the subroutine should return the character 'E'.

You should make use of the built-in subroutines INT_TO_CHAR and CHAR_TO_INT in your answer:

• CHAR_TO_INT(character) returns the integer ASCII/Unicode code for a character (e.g., CHAR_TO_INT('a') returns 97).
• INT_TO_CHAR(integer) returns the character corresponding to that ASCII/Unicode code (e.g., INT_TO_CHAR(65) returns 'A').

You can assume that the parameter passed to the subroutine will always be a lowercase letter between 'a' and 'z'.