判断是否是奇数，学习函数定义

odd.coffee

odd = (num) ->
  unless typeof num is 'number'
    throw "#{num} is not a number"
  unless num is Math.round num
    throw "#{num} is not an integer"
  unless num > 0
    throw "#{num} is not positive"
  num % 2 is 1

test = (v) -> 
  try
    console.log odd(v)
  catch e
    console.log e

test "3"
test 3.7
test -3
test 3

3