import pymc as pm

obs = np.array( [0,0,1] )

uni = pm.Uniform("prop", 0, 1)
fake_obs = pm.Bernoulli("fake_obs", uni, size=3 )

@pm.deterministic
def accept(uni = uni, fake_obs = fake_obs, obs = obs):
    if np.array_equal( fake_obs, obs ):
        return uni
    else:
        return None

mcmc = pm.MCMC([uni, fake_obs, accept] )

mcmc.sample(10000)

samples = mcmc.trace('accept')[:]

hist( samples[samples > 0] )

samples[:1000]