code: def lambdastr(args, expr, printer=None, dummify=None):
      """
      Returns a string that can be evaluated to a lambda function.
  
      Examples
      ========
  
      >>> from sympy.abc import x, y, z
      >>> from sympy.utilities.lambdify import lambdastr
      >>> lambdastr(x, x**2)
      'lambda x: (x**2)'
      >>> lambdastr((x,y,z), [z,y,x])
      'lambda x,y,z: ([z, y, x])'
  
      Although tuples may not appear as arguments to lambda in Python 3,
      lambdastr will create a lambda function that will unpack the original
      arguments so that nested arguments can be handled:
  
      >>> lambdastr((x, (y, z)), x + y)
      'lambda _0,_1: (lambda x,y,z: (x + y))(_0,_1[0],_1[1])'
      """
      # Transforming everything to strings.
      from sympy.matrices import DeferredVector
      from sympy.core.basic import Basic
      from sympy.core.function import Derivative, Function
      from sympy.core.symbol import Dummy, Symbol
      from sympy.core.sympify import sympify
  
      if printer is not None:
          if inspect.isfunction(printer):
              lambdarepr = printer
          else:
              if inspect.isclass(printer):
                  lambdarepr = lambda expr: printer().doprint(expr)
              else:
                  lambdarepr = lambda expr: printer.doprint(expr)
      else:
          # XXX: This has to be done here because of circular imports
          from sympy.printing.lambdarepr import lambdarepr
  
      def sub_args(args, dummies_dict):
          if isinstance(args, str):
              return args
          elif isinstance(args, DeferredVector):
              return str(args)
          elif iterable(args):
              dummies = flatten(
                  [sub_args(a, dummies_dict) for a in args]
              )
              return ",".join(str(a) for a in dummies)
          else:
              # replace these with Dummy symbols
              if isinstance(args, (Function, Symbol, Derivative)):
                  dummies = Dummy()
                  dummies_dict.update({args: dummies})
                  return str(dummies)
              else:
                  return str(args)
  
      def sub_expr(expr, dummies_dict):
          expr = sympify(expr)
          # dict/tuple are sympified to Basic
          if isinstance(expr, Basic):
              expr = expr.xreplace(dummies_dict)
          # list is not sympified to Basic
          elif isinstance(expr, list):
              expr = [sub_expr(a, dummies_dict) for a in expr]
          return expr
  
      # Transform args
      def isiter(l):
          return iterable(l, exclude=(str, DeferredVector, NotIterable))
  
      def flat_indexes(iterable):
          n = 0
  
          for el in iterable:
              if isiter(el):
                  for ndeep in flat_indexes(el):
                      yield (n,) + ndeep
              else:
                  yield (n,)
  
              n += 1
  
      if dummify is None:
          dummify = any(
              isinstance(a, Basic) and a.atoms(Function, Derivative)
              for a in (args if isiter(args) else [args])
          )
  
      if isiter(args) and any(isiter(i) for i in args):
          dum_args = [str(Dummy(str(i))) for i in range(len(args))]
  
          indexed_args = ",".join(
              [
                  dum_args[ind[0]]
                  + "".join(["[%s]" % k for k in ind[1:]])
                  for ind in flat_indexes(args)
              ]
          )
  
          lstr = lambdastr(
              flatten(args), expr, printer=printer, dummify=dummify
          )
  
          return "lambda %s: (%s)(%s)" % (
              ",".join(dum_args),
              lstr,
              indexed_args,
          )
  
      dummies_dict = {}
      if dummify:
          args = sub_args(args, dummies_dict)
      else:
          if isinstance(args, str):
              pass
          elif iterable(args, exclude=DeferredVector):
              args = ",".join(str(a) for a in args)
  
      # Transform expr
      if dummify:
          if isinstance(expr, str):
              pass
          else:
              expr = sub_expr(expr, dummies_dict)
      expr = _recursive_to_string(lambdarepr, expr)
      return "lambda %s: (%s)" % (args, 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 6 for calling a global function with example usage: lambdastr(args, expr, printer, dummify) and returns: unknown, expr, iterable, unknown, args, str, str, str, str