code: func (p *parser) expectType(node Node, want ValueType, context string) {
  	t := p.checkType(node)
  	if t != want {
  		p.errorf("expected type %s in %s, got %s", documentedType(want), context, documentedType(t))
  	}
  }
docs: // expectType checks the type of the node and raises an error if it
  // is not of the expected type.