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# The =~ operator returns the index of the first letter of the first matching occurence
/(rubycademy)/ =~ "https://www.rubycademy.com" # => 12
"https://www.rubycademy.com" =~ /(rubycademy)/ # => 12

# Note that the operator returns nil if no matching found
/lol/ =~ "It's not funny" # => nil

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# Flat the array layer by layer 
# 
# Insights:
#
# - Using recursion.
#

class Array
  def my_flatten(depth = nil)
    if depth.nil? || depth.is_a?(Fixnum)

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Symbol.all_symbols.length                      # => 3893
Symbol.all_symbols.grep(/Struct/)              # => [:Struct]

:dummy_symbol
Symbol.all_symbols.length                      # => 3894
Symbol.all_symbols.grep(/dummy_symbol/)        # => [:dummy_symbol]

dummy_variable = nil
Symbol.all_symbols.length                      # => 3895
Symbol.all_symbols.grep(/dummy_variable/)      # => [:dummy_variable]

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for i in 1..3 do
  puts "Iteration #{i}"

  redo if i == 1
  
  puts 'After redo'
end

# produces:
#

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def hello
  yield
end

hello do
  puts 'hello'
  
  redo
end

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[1,2,3].each do |n|
  puts "Step #{n}"
    
  n += 1 and redo if n < 2
end

# produces:
#
# Step 1
# Step 2

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for i in 1..3 do
  puts "Iteration #{i}"
  
  i += 1 and redo if i == 1
end

# produces
#
# Iteration 1
# Iteration 2

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class Hash
  def to_s
    'hash'
  end
end

h = {}

p h.to_s # => "hash"

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module Patch
  @@res = refine(Array) {}

  def self.res; @@res; end
end

p Patch.res            # => #<refinement:Array@Patch>
p Patch.res.class      # => Module
p Patch.res.ancestors  # => [#<refinement:Array@Patch>, Array, ...]

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# lib/core_ext/hash.rb

class Hash
  # monkey-patch to temporarily
  # disabling the MyLib#print_config output
  def to_json
    ''
  end
end