  Recent developments in enhanced sampling methods showed that it is possible
to reconstruct ligand unbinding pathways with spatial and temporal resolution
inaccessible to experiments. Ideally, such techniques should provide an
atomistic definition of possibly many reaction pathways, because crude
estimates may lead either to overestimating energy barriers, or inability to
sample hidden energy barriers that are not captured by reaction pathway
estimates. Here we provide an implementation of a new method [J. Rydzewski \&
O. Valsson, J. Chem. Phys. {\bf 150}, 221101 (2019)] dedicated entirely to
sampling the reaction pathways of the ligand-protein dissociation process. The
program, called \texttt{maze}, is implemented as an official module for PLUMED
2, an open source library for enhanced sampling in molecular systems, and
comprises algorithms to find multiple heterogeneous reaction pathways of ligand
unbinding from proteins during atomistic simulations. The \texttt{maze} module
requires only a crystallographic structure to start a simulation, and does not
depend on many \textit{ad hoc} parameters. The program is based on enhanced
sampling and non-convex optimization methods. To present its applicability and
flexibility, we provide several examples of ligand unbinding pathways along
transient protein tunnels reconstructed by \texttt{maze} in a model
ligand-protein system, and discuss the details of the implementation.
