I understand that operators (e.g. +, -, *, []) are nothing more than method names so that

  irb(main):027:0> x=[101,102,103,104,105]
  => [101, 102, 103, 104, 105]
  irb(main):028:0> x.[](3)
  => 104


(Those familiar with operator overloading can skip the example and go to my question below.  The example is for those who are not familiar with Ruby operator overloading.)

- - - -

I have stolen the example immediately below from
http://strugglingwithruby.blogspot.com/2010/04/operator-overloading.html


class Tester3
 def initialize ary
   @ary = ary
 end

 def [](y)
   @ary[y]
 end

 def []=(y, value)
   @ary[y] = value
 end

 def <<(y)
   @ary << y
 end

 def +(y)
   @ary << y
 end
end


focusing on
 def []=(y, value)
   @ary[y] = value
 end

- - - - -

My question is a documentation one: Where in the Ruby docs would I find the semantics of the subscript method []= defined?

That is, how would I come to know that
  x.[]=(2, 'Tuesday')
is equivalent to
  x[2]='Tuesday'