docstr: Preprocess args, expr to replace arguments that do not map
  to valid Python identifiers.
  
  Returns string form of args, and updated expr.
docstr_tok: ["Preprocess","args",",","expr","to","replace","arguments","that","do","not","map","to","valid","Python","identifiers",".","Returns","string","form","of","args",",","and","updated","expr","."]
code: def _preprocess(self, args, expr):
      """Preprocess args, expr to replace arguments that do not map
      to valid Python identifiers.
  
      Returns string form of args, and updated expr.
      """
      from sympy.core.basic import Basic
      from sympy.core.sorting import ordered
      from sympy.core.function import Derivative, Function
      from sympy.core.symbol import Dummy, uniquely_named_symbol
      from sympy.matrices import DeferredVector
      from sympy.core.expr import Expr
  
      # Args of type Dummy can cause name collisions with args
      # of type Symbol.  Force dummify of everything in this
      # situation.
      dummify = self._dummify or any(
          isinstance(arg, Dummy) for arg in flatten(args)
      )
  
      argstrs = [None] * len(args)
      for arg, i in reversed(
          list(ordered(zip(args, range(len(args)))))
      ):
          if iterable(arg):
              s, expr = self._preprocess(arg, expr)
          elif isinstance(arg, DeferredVector):
              s = str(arg)
          elif isinstance(arg, Basic) and arg.is_symbol:
              s = self._argrepr(arg)
              if dummify or not self._is_safe_ident(s):
                  dummy = Dummy()
                  if isinstance(expr, Expr):
                      dummy = uniquely_named_symbol(
                          dummy.name, expr, modify=lambda s: "_" + s
                      )
                  s = self._argrepr(dummy)
                  expr = self._subexpr(expr, {arg: dummy})
          elif dummify or isinstance(arg, (Function, Derivative)):
              dummy = Dummy()
              s = self._argrepr(dummy)
              expr = self._subexpr(expr, {arg: dummy})
          else:
              s = str(arg)
          argstrs[i] = s
      return argstrs, expr
  
imports: from __future__ import annotations
  from typing import Any
  import builtins
  import inspect
  import keyword
  import textwrap
  import linecache
  from sympy.external import import_module
  from sympy.utilities.exceptions import sympy_deprecation_warning
  from sympy.utilities.decorator import doctest_depends_on
  from sympy.utilities.iterables import is_sequence, iterable, NotIterable, flatten
  from sympy.utilities.misc import filldedent
label_desc: Use image node_id 4 for calling the _EvaluatorPrinter obj's underlying member method code with example usage: obj._preprocess(args, expr) and returns: argstrs,  expr