Write a function average$\_$unit$\_$grade$($unit$\_$name, results$)$ that accepts as input a unit name and a table of study results

of various students and units and that returns as output the average grade of the given unit. The input table is expected

to contain three columns: unit, student ID$,$ grade. You can assume that there is at least one result for the input unit

name.

For example:

$>>>$ results $=[$ 'Database', $101028,65],$

$[\text{'}Database\text{'},101022,80],$

$[\text{'}$Operating Systems', $493968,68],$

$[\text{'}$Operating Systems', $201022,59],$

$[\text{'}$Java Fundamentals', $493968,45],$

$[\text{'}$Java Fundamentals', $101022,85],$

$[\text{'}$Mathematics$\text{'},101022,71],$

$[\text{'}$Mathematics$\text{'},493968,67],$

$[\text{'}$Information Systems', $493968,75]]72\mathrm{.}569\mathrm{.}0$

Note: Your solution may NOT use any imports.