input: Write a python function to generate a binomial distribution using numpy.
  assert isinstance(binomial(10, 0.5), int)
  assert 0 <= binomial(10, 0.5) <= 10
  assert isinstance(binomial(20, 0.7), int)
  assert 0 <= binomial(20, 0.7) <= 20
output: import numpy as np
  
  def binomial(n, p):
      return np.random.binomial(n, p)