Assume $p$ is a prime and $\pi$ is the set of primes dividing $(p-1)!$. $\mathbb{Q}_{\pi}$ is the set of all rational numbers with $\pi$-numbers as denominators. A $\pi$-number is a product of elements of $\pi$. I've seen this quote two times, but with no explanation:
If $L$ is a Lie ring of nilpotency class less than $p$, and such that its underlying abelian group is a $p$-group, then we may regard $L$ as a Lie $\mathbb{Q}_{\pi}$-algebra.
Question: How can we regard $L$ as a Lie $\mathbb{Q}_{\pi}$-algebra? Why?