In the official YARD docs, there is the following example:
# @overload set(key, value)
# Sets a value on key
# @param key [Symbol] describe key param
# @param value [Object] describe value param
# @overload set(value)
# Sets a value on the default key +:foo+
# @param value [Object] describe value param
def set(*args) end
What special meaning does +:foo+ have when it is wrapped with + on either side? Does +:foo+ have a different meaning from :foo?