human
Complete the below
def lambdastr(args, expr, printer=None, dummify=False):

    ''''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))(*list(__flatten_args__([_0,_1])))\''
    '''

=====
Can you provide a the Python code you requested?
assistant
#Here is the Python code you requested.
    from sympy.matrices import DeferredVector
    from sympy import Dummy, sympify, Symbol, Function, flatten
    if (printer is not None):
        if inspect.isfunction(printer):
            lambdarepr = printer
        elif inspect.isclass(printer):
            lambdarepr = (lambda expr: printer().doprint(expr))
        else:
            lambdarepr = (lambda expr: printer.doprint(expr))
    else:
        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))
        elif isinstance(args, (Function, Symbol)):
            dummies = Dummy()
            dummies_dict.update({args: dummies})
            return str(dummies)
        else:
            return str(args)
    def sub_expr(expr, dummies_dict):
        try:
            expr = sympify(expr).xreplace(dummies_dict)
        except Exception:
            if isinstance(expr, DeferredVector):
                pass
            elif isinstance(expr, dict):
                k = [sub_expr(sympify(a), dummies_dict) for a in expr.keys()]
                v = [sub_expr(sympify(a), dummies_dict) for a in expr.values()]
                expr = dict(zip(k, v))
            elif isinstance(expr, tuple):
                expr = tuple((sub_expr(sympify(a), dummies_dict) for a in expr))
            elif isinstance(expr, list):
                expr = [sub_expr(sympify(a), dummies_dict) for a in expr]
        return expr
    def isiter(l):
        return iterable(l, exclude=(str, DeferredVector, NotIterable))
    if (isiter(args) and any((isiter(i) for i in args))):
        from sympy.utilities.iterables import flatten
        import re
        dum_args = [str(Dummy(str(i))) for i in range(len(args))]
        iter_args = ','.join([(i if isiter(a) else i) for (i, a)...