code: def compute_increments_dim1(var, irx):
      "Compute the increments of var over the dim 1."
      n1 = var.shape[1]
      n1new = n1 - irx
      inc_var = var[:, irx:n1] - var[:, 0:n1new]
      return inc_var
  
label_desc: Use image node_id 1 for calling a global function with example usage: compute_increments_dim1(var, irx) and returns: inc_var