code: def swapdim(P, dim1=1, dim2=0):
      
      if not isinstance(P, Poly):
          return numpy.swapaxes(P, dim1, dim2)
  
      dim = P.dim
      shape = P.shape
      dtype = P.dtype
  
      if dim1==dim2:
          return P
  
      m = max(dim1, dim2)
      if P.dim <= m:
          P = chaospy.poly.dimension.setdim(P, m+1)
          dim = m+1
  
      A = {}
  
      for key in P.keys:
  
          val = P.A[key]
          key = list(key)
          key[dim1], key[dim2] = key[dim2], key[dim1]
          A[tuple(key)] = val
  
      return Poly(A, dim, shape, dtype)
docs: Swap the dim between two variables.
  
      Args:
          P (Poly):
              Input polynomial.
          dim1 (int):
              First dim
          dim2 (int):
              Second dim.
  
      Returns:
          (Poly):
              Polynomial with swapped dimensions.
  
      Examples:
          >>> x,y = variable(2)
          >>> P = x**4-y
          >>> print(P)
          q0^4-q1
          >>> print(swapdim(P))
          q1^4-q0