Getting input geom from Maya deformer

mesh_from_deform

MStatus SomeDeformer::deform( MDataBlock& data, MItGeometry& itGeo, const MMatrix &localToWorldMatrix, unsigned int geomIndex )
{
    MStatus status;
    MArrayDataHandle hInput = data.outputArrayValue( input, &status );
    CHECK_MSTATUS_AND_RETURN_IT( status )
    status = hInput.jumpToElement( geomIndex );
    CHECK_MSTATUS_AND_RETURN_IT( status )
    MObject oInputGeom = hInput.outputValue().child( inputGeom ).asMesh();
    MFnMesh fnInputMesh( oInputGeom );
}