code: def bar_grad(a=None, b=None, c=None, d=None):
      """Used in multiple tests to simplify formatting of expected result"""
      ret = [("width", "10em")]
      if all(x is None for x in [a, b, c, d]):
          return ret
      return ret + [
          (
              "background",
              f"linear-gradient(90deg,{','.join([x for x in [a, b, c, d] if x])})",
          )
      ]
  
imports: import io
  import numpy
  import pytest
  from pandas import NA, DataFrame, read_csv
label_desc: Use image node_id 1 for calling a global function with example usage: bar_grad(a, b, c, d) and returns: unknown, ret