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sub 

        # Pathname.sub

(from ruby core)
---
    sub(*args)

---

Return a pathname which is substituted by String#sub.

    path1 = Pathname.new('/usr/bin/perl')
    path1.sub('perl', 'ruby')
        #=> #<Pathname:/usr/bin/ruby>

This is MURDOC! A Ruby documentation browser inspired by Smalltalk-80. It allows you to learn about Ruby by browsing through its class hierarchies, and see any of its methods.