Intersections vs. Unions

• Use the | operator (suspiciously similar to the logical OR operator)
• Widen the resulting type (more possible values)
• Useful for modeling mutually exclusive options or states

• Use the & operator (like logical AND)
• Narrow the resulting type (fewer possible values)
• Useful for combining multiple constraints or adding more required properties to existing types

type Human = {
  name: string;
  age: number;
};

type Elf = {
  name: string;
  ears: "pointy";
};

// Must have name, age, and pointy ears
type ElfHuman = Human & Elf;

// Must have name (shared between Human and Elf)
// Can have either age or ears (or both)
type ElfOrHuman = Human | Elf;

• Use unions to say your type is "this OR that"
• Use intersections to say your type is "this AND that", or sometimes more simply, "this with the additional properties of that"

Support.ai stores information about different types of users who interact with support tickets. However, there's a problem, our SupportAgentUser type is impossible to use (incompatible never).

1. Fix the SupportAgentUser type so that it correctly represents a user who can be either a SupportAgent OR an EndUser without causing a conflict.
2. Add and export a new type called SupportAdmin. It's exactly the same as a SupportAgent, but its role is always "admin".
3. Add the new SupportAdmin type as an option for the SupportAgentUser type.
4. Update getTicketCount to correctly return the user's assignedTickets if they are an admin.