  We prove a weak Harnack estimate for a class of doubly nonlinear nonlocal
equations modelled on the nonlocal Trudinger equation \begin{align*}
  \partial_t(|u|^{p-2}u) + (-\Delta_p)^s u = 0 \end{align*} for $p\in
(1,\infty)$ and $s \in (0,1)$. Our proof relies on expansion of positivity
arguments developed by DiBenedetto, Gianazza and Vespri adapted to the nonlocal
setup. Even in the linear case of the nonlocal heat equation and in the
time-independent case of fractional $p-$Laplace equation, our approach provides
an alternate route to Harnack estimates without using Moser iteration, log
estimates or Krylov-Safanov covering arguments.
