Ruby code brain teaser. Just copy paste to IRB and see for yourself. Question: why did the first example worked ? :)

magic.rb

# this Ruby method definiton will get defined successfuly
def  
  'magic !'
end

# but this Ruby method definiton will Fail with syntax error:  syntax error, unexpected keyword_end, expecting end-of-input
def   
  'magic !'
end

# Question on you: Why didn't the first example throw syntax error ? :) 
# Who will figure it out first ? :) 

We have winners 🎊 :

• First one was Sai Ram from Twitter: https://twitter.com/equivalent8/status/1083416543873196036
• Second one was user gibberishmuch from Reddit: https://www.reddit.com/r/ruby/comments/ael32x/ruby_brain_teaser_just_fun_code_example_who_will/
• Third one was user matugm in comment down bellow :)

(delay of first two answer was like 1 minute so close win :) )

Answer to this question:

First example is defined with different UTF-8 whitespace character . Second example is defined with normal regular space.

There are different "white space" characters in UTF-8 world (e.g. Tab, no-brake spaces etc) defined in UTF-8 char set http://jkorpela.fi/chars/spaces.htm, Ruby supports UTF-8 code. (Ruby since v 1.9 I think)

So if you want to mess around with your college define method like this:

def my_method 
  "what sorcery is this !?"
end

my_method # => "what sorcery is this !?" 
my_method  # => NameError (undefined local variable or method `my_method' for main:Object)

I'm Joking! Never do this ! If you do you are pure resurrection of evil and there is special place in programming hell for you 😄

Answer

1st Definition

The 1st definition has an Unicode character, specifically the character is U+2001.

It looks like an empty space.

Ruby allows creating methods using Unicode characters.

2nd Definition

The 2nd definition uses an empty space (ASCII 32, or 20 in hex).

An empty space is not a valid method name in Ruby.

Conclusion

Because the 1st definition uses an empty-looking character in the Unicode character set Ruby considers this a valid method name, but the 2nd definition uses an actual empty space, which is not valid.