docstr: Return the Foo AxisInfo.
code: def axisinfo(unit, axis):
      """Return the Foo AxisInfo."""
      if unit == 1.0 or unit == 2.0:
          return units.AxisInfo(
              majloc=ticker.IndexLocator(8, 0),
              majfmt=ticker.FormatStrFormatter("VAL: %s"),
              label="foo",
          )
  
      else:
          return None
  
file_path: matplotlib/galleries/examples/units/evans_test.py
imports: import matplotlib.pyplot
  import numpy
  import matplotlib.ticker
  import matplotlib.units
label_desc: Use image node_id 1 for calling the FooConverter obj's underlying member method code with example usage: obj.axisinfo(unit, axis) and returns: units, None