docstr: (Internal) Return a placeholder to a variable.
docstr_tok: ["(","Internal",")","Return","a","placeholder","to","a","variable","."]
code: def _make_var(self):
      """
      (Internal) Return a placeholder to a variable.
      """
      self.count_vars += 1
      return self.var_placeholder
  
imports: import random
label_desc: Use image node_id 6 for calling the EquationGenerator obj's underlying member method code with example usage: obj._make_var() and returns: self