How to use the decorator.getfullargspec function in decorator

name = caller.__name__.lower()
            callerfunc = get_init(caller)
            doc = 'decorator(%s) converts functions/generators into ' \
                'factories of %s objects' % (caller.__name__, caller.__name__)
            fun = getfullargspec(callerfunc).args[1] # second arg
        elif inspect.isfunction(caller):
            name = '_lambda_' if caller.__name__ == '' \
                else caller.__name__
            callerfunc = caller
            doc = caller.__doc__
            fun = getfullargspec(callerfunc).args[0] # first arg
        else: # assume caller is an object with a __call__ method
            name = caller.__class__.__name__.lower()
            callerfunc = caller.__call__.__func__
            doc = caller.__call__.__doc__
            fun = getfullargspec(callerfunc).args[1] # second arg
        evaldict = callerfunc.__globals__.copy()
        evaldict['_call_'] = caller
        evaldict['decorator'] = decorator
        return FunctionMaker.create(
            '%s(%s)' % (name, fun), 
            'return decorator(_call_, %s)' % fun,
            evaldict, undecorated=caller, __wrapped__=caller,
            doc=doc, module=caller.__module__)

decorator(caller, func) decorates a function using a caller.
    """
    if func is not None: # returns a decorated function
        evaldict = func.__globals__.copy()
        evaldict['_call_'] = caller
        evaldict['_func_'] = func
        return FunctionMaker.create(
            func, "return _call_(_func_, %(shortsignature)s)",
            evaldict, undecorated=func, __wrapped__=func)
    else: # returns a decorator
        if inspect.isclass(caller):
            name = caller.__name__.lower()
            callerfunc = get_init(caller)
            doc = 'decorator(%s) converts functions/generators into ' \
                'factories of %s objects' % (caller.__name__, caller.__name__)
            fun = getfullargspec(callerfunc).args[1] # second arg
        elif inspect.isfunction(caller):
            name = '_lambda_' if caller.__name__ == '' \
                else caller.__name__
            callerfunc = caller
            doc = caller.__doc__
            fun = getfullargspec(callerfunc).args[0] # first arg
        else: # assume caller is an object with a __call__ method
            name = caller.__class__.__name__.lower()
            callerfunc = caller.__call__.__func__
            doc = caller.__call__.__doc__
            fun = getfullargspec(callerfunc).args[1] # second arg
        evaldict = callerfunc.__globals__.copy()
        evaldict['_call_'] = caller
        evaldict['decorator'] = decorator
        return FunctionMaker.create(
            '%s(%s)' % (name, fun), 

return FunctionMaker.create(
            func, "return _call_(_func_, %(shortsignature)s)",
            evaldict, undecorated=func, __wrapped__=func)
    else: # returns a decorator
        if inspect.isclass(caller):
            name = caller.__name__.lower()
            callerfunc = get_init(caller)
            doc = 'decorator(%s) converts functions/generators into ' \
                'factories of %s objects' % (caller.__name__, caller.__name__)
            fun = getfullargspec(callerfunc).args[1] # second arg
        elif inspect.isfunction(caller):
            name = '_lambda_' if caller.__name__ == '' \
                else caller.__name__
            callerfunc = caller
            doc = caller.__doc__
            fun = getfullargspec(callerfunc).args[0] # first arg
        else: # assume caller is an object with a __call__ method
            name = caller.__class__.__name__.lower()
            callerfunc = caller.__call__.__func__
            doc = caller.__call__.__doc__
            fun = getfullargspec(callerfunc).args[1] # second arg
        evaldict = callerfunc.__globals__.copy()
        evaldict['_call_'] = caller
        evaldict['decorator'] = decorator
        return FunctionMaker.create(
            '%s(%s)' % (name, fun), 
            'return decorator(_call_, %s)' % fun,
            evaldict, undecorated=caller, __wrapped__=caller,
            doc=doc, module=caller.__module__)

def pandas_wrap(f, return_col=None):
    # Extract the signature arguments from this function.
    spec = getfullargspec(f)
    rtype = None
    return_sig = spec.annotations.get("return", None)
    if not (return_col or return_sig):
        raise ValueError(
            "Missing type information. It should either be provided as an argument to pandas_wrap,"
            "or as a python typing hint")
    if return_col is not None:
        rtype = _to_stype(return_col)
    if return_sig is not None:
        rtype = _to_stype(return_sig)

    # Extract the input signatures, if any:
    sig_args = []
    sig_kwargs = {}
    for key in spec.args:
        t = spec.annotations.get(key, None)

def __init__(self, func=None, name=None, signature=None,
                 defaults=None, doc=None, module=None, funcdict=None):
        self.shortsignature = signature
        if func:
            # func can be a class or a callable, but not an instance method
            self.name = func.__name__
            if self.name == '': # small hack for lambda functions
                self.name = '_lambda_' 
            self.doc = func.__doc__
            self.module = func.__module__
            if inspect.isfunction(func):
                argspec = getfullargspec(func)
                self.annotations = getattr(func, '__annotations__', {})
                for a in ('args', 'varargs', 'varkw', 'defaults', 'kwonlyargs',
                          'kwonlydefaults'):
                    setattr(self, a, getattr(argspec, a))
                for i, arg in enumerate(self.args):
                    setattr(self, 'arg%d' % i, arg)
                if sys.version < '3': # easy way
                    self.shortsignature = self.signature = \
                        inspect.formatargspec(
                        formatvalue=lambda val: "", *argspec)[1:-1]
                else: # Python 3 way
                    allargs = list(self.args)
                    allshortargs = list(self.args)
                    if self.varargs:
                        allargs.append('*' + self.varargs)
                        allshortargs.append('*' + self.varargs)