# L-10.5 MCS 260 Wed 9 Jul 2014 : q09.py
"""
Explain how to simulate an unfair coin that when flipped
returns head with probability 0.6.
Give a Python function for such unfair coin.
"""

def unfair_coin():
    "returns head with probability 0.6"
    from random import uniform
    toss = uniform(0, 1)
    if toss < 0.6:
        return 'head'
    else:
        return 'tail'

print 'simulation of an unfair coin'
while True:
    print unfair_coin()
    ANS = raw_input('continue ? (y/n) ')
    if ANS != 'y':
        break