code: def _init_edges(p2cs, c2ps):
          
          edge_from_to = []
          for parent, children in p2cs.items():
              for child in children:
                  # if child in goids_present and parent in goids_present:
                  edge_from_to.append((child, parent))
          for parent, children in c2ps.items():
              for child in children:
                  # if child in goids_present and parent in goids_present:
                  edge_from_to.append((child, parent))
          return edge_from_to
docs: Get the directed edges from GO term to GO term.