code: def add_conversion_fn(self, unit, fn):
      self.conversions[unit] = fn
  
imports: import math
  from packaging.version import parse
  import numpy
  import matplotlib.ticker
  import matplotlib.units
label_desc: Use image node_id 10 for calling the BasicUnit obj's underlying member method code with example usage: obj.add_conversion_fn(unit, fn) without return types