code: def _expand_pos_to_vec(pos, frame):
      return sum(mag * unit for (mag, unit) in zip(pos, frame))
  
imports: import pytest
  from sympy import Rational, Symbol, cos, pi, sin, sqrt
  from sympy.physics.mechanics import Force, LinearPathway, ObstacleSetPathway, PathwayBase, Point, ReferenceFrame, WrappingCylinder, WrappingGeometryBase, WrappingPathway, WrappingSphere, dynamicsymbols
  from sympy.simplify.simplify import simplify
label_desc: Use image node_id 11 for calling the TestWrappingPathway obj's underlying member method code with example usage: obj._expand_pos_to_vec(pos, frame) and returns: sum