sed with single quotes vs double quotes

sed with single quote doesn't understand variable (like $<var_name>), it takes it literally. Use sed with double quotes if you intend to replace variable ($<var_name>) with its value (<var_value>). Actually, it is a shell requirement.

You ain't gonna need it (YAGNI)

Always implement things when you actually need them, never when you just foresee that you need them.

simplicity Vs minimalism

simplicity = No complexity or Less complexity
minimalism = All but necessary