Pull a surface towards a collection of curves and points.

Input parameters:

1. Sf → Surface to tweak.
2. Cr → Optional curves to pull towards.
3. Pt → Optional points to pull towards.
4. Fx → Flexibility of the surface in areas with few or distant constraints. Flexibility is defined in the range zero (most stiff) to ten (most flexible).
5. Le → Locked edge state. If true, the surface edges will remain in place.

Output parameters:

1. Sf → Surface pulled towards curves and points.