low: an float that represent an lower bound
    high: an float that represent an upper bound
    random_state: an object of numpy.random.RandomState

def uniform(low, high, random_state):
    '''
    low: an float that represent an lower bound
    high: an float that represent an upper bound
    random_state: an object of numpy.random.RandomState
    '''
    assert high > low, 'Upper bound must be larger than lower bound'
    return random_state.uniform(low, high)