code: def test_coord_type():
      df = pd.DataFrame(
          dict(
              lat=[1.0, 2.0, 3.0],
              lon=[4.0, 5.0, 6.0],
              c=[7.0, 8.0, 9.0],
              d=["a", "b", "c"],
          )
      )
      assert utils.coord_type(df["lat"]) == "lat"
      assert utils.coord_type(df["lon"]) == "lon"
      assert utils.coord_type(df["c"]) is None
      assert utils.coord_type(df["d"]) is None
  
file_path: dtale/tests/dtale/test_utils.py
imports: from collections import namedtuple
  import mock
  import numpy
  import pandas
  import pytest
  from six import PY3
  import dtale.utils
  from tests import ExitStack
label_desc: Use image node_id 12 for calling a global function with example usage: test_coord_type() without return types