The meaning behind this method is not guaranteed to be uniform between derived types or between implementations of this package. It may represent a computed value, an explicit attribute, or be true by definition. As a computed value, the result is typically from simply testing the starting and ending positions for exact equality. This is only reliable in floating point arithmetic if these data have identical origins. As an explicit attribute, it would be persisted with the Geometry and typically denoted by a parameter in the relevant factory method. Some Geometry types are closed by definition.
Returns:
Returns 'true' if the curve is closed, and false otherwise