code: def _collapse_default(self, entry):
          
          if isinstance(entry, tuple) or isinstance(entry, list):
              sets = []
              i = 0
              while i < len(entry):
                  if isinstance(entry[i], str) and i+1 < len(entry) and isinstance(entry[i+1], list):
                      sets.append((entry[i], entry[i+1]))
                      i += 2
                  elif isinstance(entry[i], str) and entry[i] == ",":
                      i += 1
                  else:
                      sets.append((entry[i],))
                      i += 1
  
              result = []
              for s in sets:
                  if isinstance(s[0], str):
                      name = s[0].strip(",")
                  elif len(s) == 1:
                      name = self._collapse_default(s[0])
                      
                  if len(s) > 1:
                      args = self._collapse_default(s[1])
                  else:
                      args = []
                  if len(args) > 0:
                      result.append("{}({})".format(name, args))
                  else:
                      result.append(name)
  
              return ', '.join(result)
          else:
              if "," in entry:
                  return entry.split(",")[0].strip()
              else:
                  return entry.strip()
docs: Collapses the list structure in entry to a single string representing the default
          value assigned to a variable or its dimensions.