docs: def kill_def(self, variable, location, size_threshold=32):
          """
          Add a new definition for variable and kill all previous definitions.
  
          :param SimVariable variable: The variable to kill.
          :param CodeLocation location: The location where this variable is defined.
          :param int size_threshold: The maximum bytes to consider for the variable.
          :return: None
          """
  
          if isinstance(variable, SimRegisterVariable):
              if variable.reg is None:
                  l.warning('kill_def: Got a None for a SimRegisterVariable. Consider fixing.')
                  return None
  
              size = min(variable.size, size_threshold)
              offset = variable.reg
              while offset < variable.reg + size:
                  self._register_map[offset] = { location }
                  offset += 1
  
              self._defs[variable] = { location }
  
          elif isinstance(variable, SimMemoryVariable):
              size = min(variable.size, size_threshold)
              offset = variable.addr
              while offset < variable.addr + size:
                  self._memory_map[offset] = { location }
                  offset += 1
  
              self._defs[variable] = { location }
  
          else:
              l.error('Unsupported variable type "%s".', type(variable))