Syntactic sugar for using File.join to concatenate the argument to the receiver.

  require :lib / :utilities / :string

The idea is not original, but we can‘t remember where we first saw it. Waves::Ext::Symbol defines the same method, allowing for :files / ‘afilename.txt‘

[Source]

    # File lib/ext/symbol.rb, line 10
10:   def / ( s ) ; File.join( self.to_s, s.to_s ) ; end