is-agent? value is-agentset? value is-boolean? value is-<breed>? value is-command-task? value is-directed-link? value is-link? value is-link-set? value is-list? value is-number? value is-patch? value is-patch-set? value is-reporter-task? value is-string? value is-turtle? value is-turtle-set? value is-undirected-link? value
Reports true if value is of the given type, false otherwise.