src/h3/_cy/vertex.pxd (5 lines of code) (raw):
from .h3lib cimport bool, H3int
cpdef H3int cell_to_vertex(H3int h, int vertex_num) except 1
cpdef H3int[:] cell_to_vertexes(H3int h)
cpdef (double, double) vertex_to_latlng(H3int v) except *
cpdef bool is_valid_vertex(H3int v)