code: def save(
      self,
      what=None,
      filename=None,
      header=True,
      useinstant=True,
      comment=None,
  ):
      if what is None:
          what = (i for i in self.__dict__ if i[0] != "_")
      if header:
          txt = ["import numpy as np\nfrom numpy import array\n\n"]
          if useinstant:
              txt.append(
                  "from statsmodels.tools.testing import Holder\n\n"
              )
      else:
          txt = []
  
      if useinstant:
          txt.append("%s = Holder()" % self.name)
          prefix = "%s." % self.name
      else:
          prefix = ""
  
      if comment is not None:
          txt.append("{}comment = '{}'".format(prefix, comment))
  
      for x in what:
          txt.append(
              "{}{} = {}".format(prefix, x, repr(getattr(self, x)))
          )
      txt.extend(["", ""])  # add empty lines at end
      if filename is not None:
          with open(filename, "a+", encoding="utf-8") as fd:
              fd.write("\n".join(txt))
      return txt
  
file_path: statsmodels/statsmodels/sandbox/tests/maketests_mlabwrap.py
imports: import numpy
  from numpy.testing import assert_array_almost_equal
  from numpy import array
label_desc: Use image node_id 2 for calling the HoldIt obj's underlying member method code with example usage: obj.save(what, filename, header, useinstant, comment) and returns: txt