Renders authoritative source hash as HTML.
@param input [Hash] authoritative source hash. @return [String]
TODO Maybe support string inputs.
def display_authoritative_source(input)
ref, clause, link = input.values_at("ref", "clause", "link") rescue nil
return "" if ref.nil? && link.nil?
ref_caption = escape_once(ref || link)
ref_part = link ? %[<a href="#{link}">#{ref_caption}</a>] : ref_caption
clause_part = clause && escape_once(clause)
[ref_part, clause_part].compact.join(", ")
end