$3.$a$)$ Write the code that converts customersOfficeSupplies into a set $(2\mathrm{.}5$ pts$),$ customersTechnologies into a set $(2\mathrm{.}5$ pts$),$ and customersFurniture into a set $(2\mathrm{.}5$ pts$)$

$3.$b$)$ Write the code that returns the number of unique customers who purchased office supplies $(2\mathrm{.}5$ pts$),$ the number of unique customers who purchased technologies $(2\mathrm{.}5$ pts$),$ and the number of unique customers who purchased furniture $(2\mathrm{.}5$ pts$)$

$3.$c$)$ Write the code that returns the customers who purchased either office supplies or technologies $(5$ pts$)$

$3.$d$)$ Write the code that returns the customers who purchased office supplies, technologies and furniture $(5$ pts$)$

$3.$e$)$ Write the code that returns the customers who purchased office supplies, but did not purchase technologies $(5$ pts$)$