code: def test_uniquecols():
      data = pd.DataFrame(
          {
              "x": [1, 2, 3, 4],
              "y": ["a", "b", "c", "d"],
              "z": [8] * 4,
              "other": ["same"] * 4,
          }
      )
      data2 = pd.DataFrame({"z": [8], "other": ["same"]})
      result = uniquecols(data)
      assert result.equals(data2)
  
file_path: plotnine/tests/test_utils.py
imports: import itertools
  import random
  import string
  import warnings
  import numpy
  import pandas
  from plotnine._utils import _margins, add_margins, join_keys, match, ninteraction, pivot_apply, remove_missing, uniquecols
  from plotnine.data import mtcars
label_desc: Use image node_id 7 for calling a global function with example usage: test_uniquecols() without return types