Refactoring string concatenations

[saikumarmk]

In place of say:

output = ""
for unit in prereqs_list:
    output += f'{unit}\n'

It is much cleaner to construct a string in one go as the string concatenate operator creates a new string (strings are immutable by default). While operations such as these are inconsequential due to scale, it is good practice to do the following:

output = "\n".join(prereqs_list)

If you're iterating over a more complex structure and need to extract some terms, you can do it as follows:

output = ",".join([f"{data['blah']}: {data['foo']}" for data in bar])

Cutting down to one line. This also solves the asymmetry of requisites where you may get a result like "MTH1030, ENG1005," with a trailing comma. This can e found in the unit_embed.py file, on lines 35, 43, 47, and 50-54.