code: def dup_chebyshevu(n, K):
      """Low-level implementation of Chebyshev polynomials of the second kind."""
      if n < 1:
          return [K.one]
      m2, m1 = [K.one], [K(2), K.zero]
      for i in range(2, n + 1):
          m2, m1 = m1, dup_sub(
              dup_mul_ground(dup_lshift(m1, 1, K), K(2), K), m2, K
          )
      return m1
  
imports: from sympy.core.symbol import Dummy
  from sympy.polys.densearith import dup_mul, dup_mul_ground, dup_lshift, dup_sub, dup_add
  from sympy.polys.domains import ZZ, QQ
  from sympy.polys.polytools import named_poly
  from sympy.utilities import public
label_desc: Use image node_id 6 for calling a global function with example usage: dup_chebyshevu(n, K) and returns: m1, list