feat: equals type guards

[tpluscode]

It can be useful to use equals to narrow down a term's type. For example, in my code I have

if (functionPtr.term.equals(dashSparql.in) || functionPtr.term.equals(dashSparql.notin)) {
  return new InExpression(pointer.term, functionPtr.term, expressionList)
}

export class InExpression extends FunctionExpression {
  constructor(exprTerm: Term, funcTerm: typeof dashSparql.in | typeof dashSparql.notin, args: NodeExpression[]) {
}

See that funcTerm requires Named Node with one of very specific URIs. Right now, even though the type is ensured by the if statement, the type of functionPtr.term is a "plain" NamedNode, causing a TS error.

By adding this is T return type assertion to equals, this type is narrowed down in the body of the condition.

[changeset-bot]

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Latest commit: 6206428

The changes in this PR will be included in the next version bump.

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Name	Type
@rdfjs/types	Minor

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