PK_ERROR_code_t   PK_EDGE_ask_curve
(
--- received arguments ---
PK_EDGE_t         edge,             --- an edge

--- returned arguments ---
PK_CURVE_t *const curve             --- its curve (possibly PK_ENTITY_null)
)


This function returns the curve of the given edge, if it has one, otherwise
PK_ENTITY_null.


If there is no curve attached to the edge, the edge may be tolerant, in which
case curve geometry will normally be attached to each of its fins.