Shiny by RStudio

Include content only once

singleton(x, value = TRUE)



x A tag, text, HTML, or list.
value Whether the object should be a singleton.


Use singleton to wrap contents (tag, text, HTML, or lists) that should be included in the generated document only once, yet may appear in the document-generating code more than once. Only the first appearance of the content (in document order) will be used.