Create a Rio referencing Rio#to_str + arg.to_str

 rio('afile') + '-0.1'   #=> rio('afile-0.1')

Create a new Rio referencing the result of applying ::String#gsub to the value returned by Rio#to_s. So:

 ario.gsub(re,string)

is equivelent to

 rio(ario.to_s.gsub(re,string))

See also sub +

Create a new Rio referencing the result of applying ::String#sub to the value returned by Rio#to_s. So:

 ario.sub(re,string)

is equivelent to

 rio(ario.to_s.sub(re,string))

See also gsub, +