Get the pathways adjacent to this pathway in the network

        Parameters
        -----------
        pathway : str

        Returns
        -----------
        list(str), a list of pathways adjacent to the input pathway

def get_adjacent_pathways(self, pathway):
        """Get the pathways adjacent to this pathway in the network

        Parameters
        -----------
        pathway : str

        Returns
        -----------
        list(str), a list of pathways adjacent to the input pathway
        """
        vertex_id = self.pathways[pathway]
        adjacent = self.vertices[vertex_id].get_adjacent_vertex_ids()
        adjacent_pathways = []
        for adjacent_id in adjacent:
            adjacent_pathways.append(self.get_pathway_from_vertex_id(
                adjacent_id))
        return adjacent_pathways