Support for the Ruby 2.4 series has ended. See here for reference.
Returns uri converted to a URI object.
 
               # File uri/common.rb, line 733
def URI(uri)
  if uri.is_a?(URI::Generic)
    uri
  elsif uri = String.try_convert(uri)
    URI.parse(uri)
  else
    raise ArgumentError,
      "bad argument (expected URI object or URI string)"
  end
end