Built recursive and iterative methods to return the Fibonacci sequence up to a given n, then ran benchmarks to test performance

fibonacci.rb

def recursive_fib(n)
  # sets the first two values (0 and 1) by default 
  if n < 2
    return n
  # if n is greater than or equal to 2, the nth number in the fibonacci
  # is the sum of the function called on n-1 and the function called on
  # n-2
  else
    return recursive_fib(n-1) + recursive_fib(n-2)
  end
end

def iterative_fib(n)
  # set initial values of the first two fibonacci numbers (?)
  a = 0
  b = 1
  # loop n times
  n.times do
    # set a placeholder to be equal to a (in the base case, 0)
    # in the second loop, it will equal 1
    # in the third loop, placeholder = 1
    # in the fourth loop, placeholder = 2
    placeholder = a
    # set a to equal b (in the base case, a will now equal 1)
    # in the second loop, a will now equal 1
    # in the third loop, a = 2
    # in the fourth loop, a = 3
    a = b
    # set b to equal placeholder + b (1 + 0)
    # in the second loop, it will be 1 + 1 = 2
    # in the third loop, b = 1 + 2 = 3
    # in the third loop, b = 2 + 3 = 5
    b = placeholder + b
  end
  # in the first loop, it'll return 1
  # in the second loop, it'll return 1
  # in the third loop, it'll return 2
  # in the fourth loop, it'll return 3
  return a
end

puts recursive_fib(4)
puts iterative_fib(4)

require 'benchmark'
num = 45
Benchmark.bm do |x|
  x.report('recursive_fib') { recursive_fib(num) }
  x.report('iterative_fib') { iterative_fib(num) }
end