Works like sculpt deform in Maya.
A SimpleMod scripted plug-in modifier which inflates or pinches
an object according to the transformation of the modifier's gizmo, the radius and falloff parameters.
The Radius is the length of the offset a vertex would get if it's distance
from the gizmo evaluates as zero. This parameter can be set to a negative value as well to create a pinch effect.
The Falloff determines how far from the gizmo will the bubble effect the deformation.
This modifier works like every SimpleMod, on every point on the object or current point selection in the object. These points may be mesh vertices, spline vertices, NURBS CVs, and so on.