Have a Strategy that does not uniformly choose between different strategies
Hypothesis does not allow users to control the probability of various choices within a strategy.  You should not use undocumented interfaces either - hypothesis.internal is for internal use only and could break at any time!
I strongly recommend using C = st.one_of(A, B) and trusting Hypothesis with the details.
I'd like to create a strategy C that, 90% of the time chooses strategy A, and 10% of the time chooses strategy B.
The random python library does not work even if I seed it since each time the strategy produces values, it generates the same value from random.
I looked at the implementation for OneOfStrategy and they use 
            i = cu.integer_range(data, 0, n - 1)
to randomly generate a number
cu is from the internals
import hypothesis.internal.conjecture.utils as cu
Would it be fine for my strategy to use cu.integer_range or is there another implementation?