test.rb

def is_a_power_of_two?(n)
  return false if n.is_a?(Float)
  (n-1)& n == 0 if n != 0
end 

def logb2(n)
  if is_a_power_of_two?(n)
    return n.to_s(2).match(/1(0*)/)[1].length
  else
    false
  end
end