Return two copies of x, if x is not nil


def double(x)
  return nil if x == nil   # Return prematurely
  return x, x.dup          # Return multiple values
end

1.	Returning a Value from a Method
2.	Ruby returns the last value calculated, you can omit the return keyword if you want.
3.	Return a Value from a Method
4.	Returning Multiples Values from a Method
5.	Because it's returning multiple values from a method, Ruby returns an array:
6.	Ruby makes it easy to handle multiple return values - no need to work with arrays explicitly at all.
7.	Return values from function without using return statement
8.	String interpolation with method call
9.	Return the index of the first occurrence of target within array or nil

Return two copies of x, if x is not nil : return « Method « Ruby