test_binomial = ->
  run_test [
    "binomial(12,6)",
    "924",

    "binomial(n,k)",
  #  "1/(factorial(k))*factorial(n)*1/(factorial(-k+n))",
  #  "factorial(n)/(factorial(k)*factorial(-k+n))",
    "n!/(k!*(-k+n)!)",

    "binomial(0,k)",
  #  "1/(factorial(k))*1/(factorial(-k))",
  #  "1/(factorial(k)*factorial(-k))",
    "1/(k!*(-k)!)",

    "binomial(n,0)",
    "1",

    "binomial(-1,k)",
    "0",

    "binomial(n,-1)",
    "0",
  ]