docstr: Return the default unit for x or None.
docstr_tok: ["Return","the","default","unit","for","x","or","None","."]
code: def default_units(x, axis):
      """Return the default unit for x or None."""
      if np.iterable(x):
          for thisx in x:
              return thisx.unit
      return x.unit
  
imports: import math
  from packaging.version import parse
  import numpy
  import matplotlib.ticker
  import matplotlib.units
label_desc: Use image node_id 3 for calling the BasicUnitConverter obj's underlying member method code with example usage: obj.default_units(x, axis) and returns: x, thisx