code: def dup_add(f, g, K):
      """
      Add dense polynomials in ``K[x]``.
  
      Examples
      ========
  
      >>> from sympy.polys import ring, ZZ
      >>> R, x = ring("x", ZZ)
  
      >>> R.dup_add(x**2 - 1, x - 2)
      x**2 + x - 3
  
      """
      if not f:
          return g
      if not g:
          return f
  
      df = dup_degree(f)
      dg = dup_degree(g)
  
      if df == dg:
          return dup_strip([a + b for a, b in zip(f, g)])
      else:
          k = abs(df - dg)
  
          if df > dg:
              h, f = f[:k], f[k:]
          else:
              h, g = g[:k], g[k:]
  
          return h + [a + b for a, b in zip(f, g)]
  
imports: from sympy.polys.densebasic import dup_slice, dup_LC, dmp_LC, dup_degree, dmp_degree, dup_strip, dmp_strip, dmp_zero_p, dmp_zero, dmp_one_p, dmp_one, dmp_ground, dmp_zeros
  from sympy.polys.polyerrors import ExactQuotientFailed, PolynomialDivisionFailed
label_desc: Use image node_id 23 for calling a global function with example usage: dup_add(f, g, K) and returns: g, f, dup_strip, unknown